Limiting current?

Good day, I am interested in an effective way of limiting current for a TEC application. This application involves using the TEC's (12V @ 1A) to reduce the incoming air temperature in a noise isolating enclosure from ambient temp to about  5-10 deg C cooler. In doing some research on implementing the TEC's I have found that these units operate at their greatest efficiency around 1/3 of max amp input and lower when you do not have a large heat load to "pump" away. So all of this being said I would like to operate a number of TEC's at  this low amperage range, and to be able to cap their maximum current draw between .1 and .3 amp.  Any input would be greatly appreciated, thanks

Question by MatthewSternbauer 2 years ago  |  last reply 2 years ago


Current drive letter in batch? Answered

I used to have a short code block that would set the drive letter that it's in, to a variable. If I had the batch file on my flash drive (G:), it would set:G:\If I had the file on my desktop, it would set:C:\Does any one understand what I'm talking about? For the life of me, I can't remember that script...

Question by Arbitror 9 years ago  |  last reply 3 years ago


Battery Power Capability (C)

I'm trying to understand a little bit more about batteries. I've learnt so far: "Volts,  amps, and  watts measure electricity. Volts measure the “pressure” under which electricity flows. Amps measure the amount of electric current. Watts measure the amount of work done by a certain amount of current at a certain pressure or voltage." Now I'm interested in knowing the maximum amount of energy you can draw from a battery at any one time. I presume you can't instantly drain a batteries full energy capacity at any one time. I have read that: "The way the power capability is measured is in C's. A C is the Amp-hour capacity divided by 1 hour. So the C of a 2Ah battery is 2A. The amount of current a battery 'likes' to have drawn from it is measured in C. The higher the C the more current you can draw from the battery without exhausting it prematurely. Lead acid batteries can have very high C values (10C or higher) , and lithium coin cells have very low ones (0.01C)" Am I write in saying a 1.2V 1200mAh has a power capability of 1.2C? In which case I should only ever draw 1.2C or less to preserve the battery? How do I increase this amount when using 2 batteries, if I wire two batteries together does the power capability increase to 2.4C for the above example batteries? If so do I have to wire them in parallel or series for this to work? Thank you.

Topic by jakespikey 7 years ago  |  last reply 7 years ago


How much current would this draw? Answered

I am trying to build and audio amp and i need to know what voltage/current my wall plug should be. It says it in the pdf i think but i need another persons opinion. here is the link to the amp, pdf is a  link on page. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq;=92254311&uq;=634236322019806587 Also would it be possible to feasibly power this for a short time on batteries (aa or c size?) I know i am burdening you already, but what wattage resistors should i get? P.S I am building off of figure 15 on page 7 THANK YOU! =D

Question by astroboy907 8 years ago  |  last reply 8 years ago


Is it possible to increase motor speed by adding current?

Hi there, I want to increase my 5 volts cooling pad speed by hacking it. I've tried increase the voltage, but the motor died after next hours. I have a plan to increase the current without increase the voltage, but it's doubtful to be worked. Somebody got any idea? Thank you

Question by AthaariqA 2 years ago  |  last reply 2 years ago


How much Current does an Arduino Duemilanove Draw? Answered

How much Current(in MA) does an Arduino Duemilanove Draw While:Running Blinkenlight?Running code not turning any lights on?Also How much would it draw under those conditions when it is receiving 5V and through the regulator in the DC jack?

Question by ReCreate 9 years ago  |  last reply 9 years ago


Will transistors in parallel hold up to a higher current? Answered

I'm trying to create a simple PWM speed controller.  The only problem is that this controller will need to be able to stand up to 100 amps (probably more, but let's just leave it at 100 for simplicity).  A typical 2n3055 transistor can stand up to 15 amps when properly cooled.  Will wiring 8 of these transistors in parallel be enough to stand the 100 amp current?

Question by aeronut01 8 years ago  |  last reply 8 years ago


what makes a RC LiPo discharge rate (C) is different ?

Exmple : 7.2v 800mAh 15C, 11.1 2200mAh 20C

Question by Rendydevara 7 years ago  |  last reply 7 years ago


Can I use a 10 amp 120 volt relay for more then 10 amps if the voltage is lower? Answered

I am currently working on a mini A/C with a TEC that draws 12V and 12 amps and the relays I want to control it with have a rating of 10 amps 120v. not sure if it is as simple as this but 10A*120V=1200 watts. While 12A*12V=144 watts so in my eyes this would work because there is much less power flowing through the relay but I would like to request advice from someone who is a bit more knowledgeable then I. Help would be greatly appreciated thanks a bunch. Harry

Question by harry88 4 years ago  |  last reply 4 years ago


how do you make a voltage splitter to dividea current in two so they act as if they were coming from different sources

Hello, i am building and rc tank that uses 4 relays to power 2 motors in both forwards motion and backwards, all running from 1 battery pack. however ive hit a snag in my developements in which the single battery pack was actually bypassing the relays as it connected to the terminals of the motors, therefore not allowing me to use one relay to apply +/- power the motor via the battery and useing another to apply -/+ via another. my only logical solution at the time was to remove 1 of the 3 battery packs being used (were each batpack contains 10X1.2v 3AH AA batteries), and arrange it so that 1 pack powerd the motor when going in reverse, and the other two were to power the motor going forwards, and although this means that my tank would run fine, and the subtraction of 1 pack doesnt make a difference power wise to the motors as they run at max efficiency with 2 packs, its still a real hassle to recharge them as i cant just charge em all up at once, the reverse motor battery pack may run out before the forwards, and vice versa, giving me less time to run the tank, than if they were together. so now you know my problem, what i need is a solution, how can i make a voltage splitter or current splitter or whatever, so that it can divide a current in two so that if i were to connect a positive wire from current 1, and negative wire from current 2 it would not complete a circuit, and basically act like they come from two totally different sources. this was what i was doing until i realised that when i tested the motors in either direction, it was actually going forwards each time i switched it on, after swaping the wires around when it would just run the motor if the relays werent even turned on. my tank has nothing yet on its motors shafts like gears or nothing, it was a simple mistake. so please, can anyone help me?

Question by oldmanbeefjerky 8 years ago  |  last reply 8 years ago


how can i turn a 3 volt current into a 12 volt continuous current to keep a relay switch open? Answered

I am building an r/c tank as some may already know from previous questions, anyway my batteries came in and now i have gone to my local jarcar shop only to find out that the relays i require to run a 12 volt 9 amp current need 12 volts at 150ma to stay open! but the reciever from a toy rc truck can only supply 6 volts for which the motors run off and another 3 volts for which the servo runs off . so how can i amplifie this current into 12 volts continuous to keep the relay open? i know whats needed, the voltage will be doubled but the amphours will be cut in halfe or quarters or whatever the opposit of what is needed to make a 12 volt current. i need to know what it is i need and how to assemble it , i am good with most instructions and im presuming that this should be quite simple and similar to that of a solar powerd sla battery charger.

Question by oldmanbeefjerky 8 years ago  |  last reply 6 years ago


Does anyone know of a electric air conditioner that runs off of the cars D/C or using a A/C converter

Does any one know of a air conditioner that could be used in a car, that runs off of the D/C current of a car of using a converter to use A/C power. I am trying to aircondition my car without using all the gas from when the compressor is on. Any ideas or suggestions? possible even solar energy if anyone knows enough about this.

Question by tepfy 9 years ago  |  last reply 4 years ago


what type of resistor should i use if i have 3 of these LED's in a series with a 12v batter?

 LED Specs Size (mm) : 5mm Lens Color : Water Clear Reverse Current (uA) : <=30 Life Rating : 100,000 Hours Viewing Angle : 180 Degrees Absolute Maximum Ratings (Ta=25°C) Max Power Dissipation : 80mw Max Continuous Forward Current : 24mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V Lead Soldering Temperature : 240°C (<5Sec) Operating Temperature Range : -25°C ~ +85°C Preservative Temperature Range : -30°C ~ +100°C and i'm using a B3v-250c   3 LED array to hook them up that i bought from ebay

Question by JustXtreme 9 years ago  |  last reply 9 years ago


I'm back everybody!

Hi everyone, I'm back from the TSA national competition in Orlando Florida! I got a 2nd place trophy in a challenge called electrical applications, which is basically electronic tests and circuits and what not. I personally think the competition was poorly planned and some of the questions were trick questions (although they wouldn't seem trick to a more ignorant person, for example: Hooking a 9volt battery in parallel with an existing 9volt battery in a circuit will: a) decrease current in the circuit b) increase the current in the circuit c) double the current in the circuit d) the current in the circuit will stay the same The answer could be B,C, or D, yet only one can be the right one. 2nd best in the nation, wooo here's a pic of my trophy:

Topic by guyfrom7up 10 years ago  |  last reply 10 years ago


Is there a way to &quot;rename&quot; my hard drive so the computer thinks its a different letter? Answered

To be more specific. I need to "rename" the "C" drive (alternate hard drive) to think its the "D" drive (currently the 'core' of my OS) Is this possible?

Question by B.F.L.M 9 years ago  |  last reply 9 years ago


A Level choices

 I'm not after anything in particular here just want some opinions. After recently applying to my local sixth form college I'm curious as to...well I just want to talk really. My options are: 1.Chemistry 2.Physics 3.Mathematics 4.DT: Product design - Materials Reserve:Computing GCSE: P= predicted grade, C = current grade (Or already gained GCSE), L/10 = how much I enjoy, G/10 = how capable I am. Maths: P= A*, C=V. high A, L8/10, G7/10 Physics: P=A*, C=A*, L9/10, G9/10 ICT: P=D(distinction), C=D, L7/10, G10/10 BPE: P=A*, C=A/A*, L6/10, G8/10 Chemistry: P=A*, C=A*, L9/10, G9/10 DT (Electronics):P=A*, C=A*, L9/10, G9/10 Catering: P=A*, C=A, L5/10, G8/10 Music: P=A/A* , C=B/A, L5/10, G7/10 Biology: P=A/A*, C=A/A*, L8/10, G7/10 English Lit.: P=A*, C=A, L6/10, G6/10 English Lang.: P=A/A*, C= B/A, L6/10, G6/10 PE: No GCSE Anyone else recently applied for sixth form? Currently at sixth form college or university? Any advice? I reckon I am going to end up (sounds so negative) in Engineering or Science, whether I choose University or an apprenticeship etc. ANY advice appreciated.

Topic by DELETED_zoltzerino 9 years ago


Induction Charging ? Answered

OK, I have disassembled a old electric tooth brush and I am trying to reduce the size and one of the things I have deemed unnecessary is the PCB that runs the timer built into the toothbrush. However, one thing I am wary of at this moment is that the toothbrush is a induction Charger which is a A/C and I don't know if I can just remove the board and be OK or do I need to rectify the current into D/C to continue charging the battery. If the latter is the case what do I need to achieve this?

Question by Jayccob 3 years ago  |  last reply 3 years ago


How to call an api with nodemcu from this wesite:http: (//davidayala.eu/current-time/)?

Http://davidayala.eu/current-time/ The website above offers free Timezone APIs. I have been trying to request the API with my esp8266 NodeMCU, but still, i get no response. Can anyone please demonstrate to me with a code sample how it's supposed to be done? I will be posting my code soon. The following is my code (In arduino IDE) for my NodeMCU #include String result; char host[]="script.google.com"; WiFiClient client; void setup() { // put your setup code here, to run once: Serial.begin(9600); WiFi.begin("Faiz", "hautepackard"); while(WiFi.status() != WL_CONNECTED){ Serial.print("."); delay(500); } Serial.println("Connected!"); Serial.println(WiFi.localIP()); } void loop() { Time(); delay(3000); } String url = "/macros/s/AKfycbyd5AcbAnWi2Yn0xhFRbyzS4qMq1VucMVgVvhul5XqS9HkAyJY/exec"; void Time(){ if (client.connect(host, 443)) { //starts client connection, checks for connection client.print(String("GET ") + url + " HTTP/1.1\r\n" + "Host: " + host + "\r\n" + "Connection: close\r\n\r\n"); Serial.println("Server is accessible"); } else { Serial.println("connection failed"); //error message if no client connect Serial.println(); } result = ""; while (client.available()) { //connected or data available char c = client.read(); //gets byte from ethernet buffer result = result+c; } Serial.println(result); client.stop(); //stop client Serial.println("end of function"); } And this is what i get in the Serial monitor: ........Connected! Server is accessible end of function Am i going wrong anywhere in the code? Please help this burning question.

Question by Techovator0819 1 year ago  |  last reply 1 year ago


I have 20 leds I want to hook in series. can someone tell me how to do it? Answered

Here are the specs of the bulbs. Parameter Typ Max Unit Luminous Intensity 4180min 10000 mcd Viewing Angle 24°~30° 23° Deg Forward Voltage 3.3- 3.6 V Reverse Voltage ~ ~ V Forward Current 20 mA Wavelength ----nm Operating Temperature Range -40°C to -80°C Storage Temperature Range -40°C to -80°C Lead Soldering Temperature(4mm from body) 260°C for 5 seconds Datasheet Download Color?

Question by sgtfarrar 9 years ago  |  last reply 9 years ago


can i power a coil gun with 11.1 v with 4400mah with a c rating of 50?

I have 2 x 11.1. volts 2200mAh in parallel which gives me double the current but the same voltage. will this power a multi staged coil gun?

Question by icey.hood 4 years ago  |  last reply 4 years ago


WheatStone bridge

Recently i studied the wheatstone bridge in me physics book in class but i could not understand it properly. I asked the teacher about my confusion but he also dont know. i have posted the picture of topic(wheatstone bridge). My question is ;1.Why current I1 is following through point A to D in loop ADBA. 2.Why current I2 is following through point D to C in loop DCBD.My confusion is that why current are following through these two paths. As current always flow through level of a higher potential to a level of lower potential but here it seems opposite.

Topic by DabuHackker 8 months ago  |  last reply 8 months ago


how can I use a mobile phone dmtf tones to turn on PC parallel port pins on and off using VB, C or C++ code?

I need to be able to turn on ac powered lights from my pc parallel port using my phone. The set up I have uses two relays to put on the ac lines. Am currently using a web interface to do it. I dont want to rely on SMS. Suggestions that use SMS are welcome though. Any help will be appreciated.

Question by firstkenyan 9 years ago  |  last reply 7 years ago


Help finding an appropriate relay for a 12v 50amp power source!? Answered

I need to control a 12 volt 50 amp power source with a relay via arduino, and the relay that I am currently using isn't rated for such a high amperage. I'm fairly new to electronics, and would appreciate the help! For reference, my current relay: songle srd-05vdc-sl-c

Question by meanbean 6 years ago  |  last reply 6 years ago


I am an electrical engineer student and I would like to create a personal project, ideas?

Hi, I would like to create a project involving C programming with the arduino. I have some ideas (like an autonomous plant watering system but it looks to easy and basic), but I would like a project that will reflect my ability to learn C programming (I'm currently learning C++  ). Also, I don't wan't to copy any of the arduino tutorials. Do you have any ideas? Thank you

Question by napstercc 7 years ago  |  last reply 7 years ago


How do I fix my modded Xbox? Answered

Long story short, in the C: drive of the original Xbox, the xboxdash.xbe was renamed to xboxdash2.xbe. Tthe new file currently name xboxdash.xbe didn't work, so now the Xbox won't boot and I get an error message and red blinking lights when I turn it on. Is there any way I can access the C: drive and rename the actual xboxdash.xbe file back to normal so it will boot again?

Question by jfg2597 9 years ago  |  last reply 9 years ago


How to limit A/C current draw from gird and draw power from secondary grid tied solar inverter ?

Micro grid tie inverters are an excellent power source and can be linked together to generate energy, however they do not function when grid is down, this is for the safety of line workers. In a real world scenario I want to ensure that all power is drawn from the energy produced by the micro solar inverters as the primary source while it can produce power and not from the grid which will act as a secondary power source, this will require some sort of current limiting solution from the grid without reducing the voltage to keep the inverter working.   For the safety of line workers I would like to have an automatic transfer switch which will have both the primary power source from grid and a tertiary inverter backed battery backup so that when the grid is off, the power is drawn from the Inverter and there is no power fed back into the line keeping lineworkers safe and since pure sine wave produced by the inverter can activate the grid-tie inverters and it should theoretically increase the VA of the UPS to the size of the installed Grid-tie micro inverter capacity, the automatic transfer switch should take care of switching between grid when power is on and to the backup inverter when power is off.  TIA for any advice in this regard !

Topic by Ruben GeradM 2 years ago  |  last reply 2 years ago


help me in making power supply for my "Drill m/c (DC)?

I got a cordless drill machine. its battery pack is ruined. so now I want to make it corded one so that it work directly with my ac mains (240Vac). the power rating is 13.2V and 2amp(at constant operation, at starting current is very high >10amp). so I want a Dc power supply approx. 30W at 15V and 2Amp. help me in making this. give me the components required and circuit diagram(I want to use transformer). also I want to put this power supply in the battery pack box.

Question by tajeshwar28 4 years ago  |  last reply 4 years ago


are these sufficient specs for a multimeter?

These are the specs off a multimeter im about to buy. are these enough to do electronic projects off instructables.com, fixing electronics, and etc? if not then what do i need then? thanks DC Voltage: 200mV-1000V AC Voltage: 2V-700V Temperature: 20°-1000°C Resistance: 200Ω-20MΩ DC Current: 2mA-20A AC Current: 20mA-200mA Capacitance: 2nF-20µF Frequency: 10Hz-20kHz  

Topic by leader1 9 years ago  |  last reply 9 years ago


Chat

Hellow everyone, i kinda run into this site, and this group, and i made an acc as you can see :3 i kinda made a chat today in batch, pretty simple and using Dropbox, but i haz some ideas with powershell and using an FTP. but here is a pic of how it works and the code ofcorse! code client: @echo off SET name=%username% color 0a :main cls echo ############################# echo #welcome to the dropbox chat# echo ############################# echo. echo Make your sellection bellow! echo. echo [1]-Collor menu echo [2]-Chat name echo [3]-Chatroom echo [4]-Info (waar normaal nooit iemand kijkt) echo name: %name% echo. :sellect1 set /p C=Sellection: if "%C%"=="1" goto collor if "%C%"=="2" goto name if "%C%"=="3" goto chat1 if "%C%"=="4" goto info if Else goto main /goto main :chat1 echo %name% just joined the chat>>chat.txt goto chat :collor cls echo ############ echo #COLLORS!!!# echo ############ echo. echo pick a collor echo. echo [1]- White echo [2]- Green echo [3]- Red echo [4]- Purple echo [5]- Blue echo [6]- Yellow echo. echo [0]- Main menu echo. :sellect2 set /p C=Collor: if "%C%"=="1" color F if "%C%"=="2" color A if "%C%"=="3" color C if "%C%"=="4" color D if "%C%"=="5" color B if "%C%"=="6" color E if "%C%"=="0" goto main goto collor :name cls echo ############### echo #create a name# echo ############### echo. echo Type in your name (please dont use spacebar) echo. :sellect3 set /p C=Name: SET name=%C% goto main :chat cls echo ######## echo #-CHAT-# echo ######## echo. echo Every msg you type will be added in the chat.txt file, echo so chek on that file for the chat. echo. :sellect3 set /p C=: echo [%time%] %name%:%C%>>chat.txt if "%C%"=="/clear" goto del if "%C%"=="/afk" echo %name% is currently afk>>chat.txt if "%C%"=="/back" echo %name% is no longer afk>>chat.txt if "%C%"=="porn" echo %name% is a perv>>chat.txt goto chat :del del chat.txt goto chat code reader: @echo off :1 cls type chat.txt PING -n 2 127.0.0.1>nul goto 1 thats a bit it, kinda simple i know, but its fun to use and fun to make, feedback is always welcome! ^__^ have a great day/night bye!

Topic by dwngrt 6 years ago  |  last reply 6 years ago


Help with resistor calculator for LEDs

Hi everyone, I decided to try and build some LED lighting and found a few online resistor calculators but, I'm not exactly sure what to put for the voltage drop and the LED current (other than using the generic suggestions from the online calculators). So here are my questions... Is the "forward voltage" what you enter for the "voltage drop"? If so, do you use the lower or higher number? For the LED current, do I use the "max cont. foward current" or should I just put in the suggested 20mA? what kind of a difference would one be over the other? These are the specs given for the LED I'm going to be using (minus the unimportant stuff). Forward Voltage (V) : 3.2 ~ 3.8 Reverse Current (uA) : <=30 Absolute Maximum Ratings (Ta=25°C) Max Power Dissipation : 80mw Max Continuous Forward Current : 30mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V Thanks in advance.

Topic by GSXR 8 years ago  |  last reply 8 years ago


Is there any kind of clear material that changes clarity when electricity is passed through? Answered

I mean a glass-like material that, when electricity passes through it, acts more like frosted glass. Not LCD though, because that only gets darker.

Question by Super_Nerd 7 years ago  |  last reply 7 years ago


whats the best motor and ESC to use for a high torque r/c tank?

I am currently building an r/c tank, but i am having trouble finding a suitable motor and ESC that will allow it to go realy fast ( high speed tank). all i can find are brushless motors that require 30A at 6-12v, the same goes for the esc's, and i have no idea were to get that sort of power as i only have access to a 9.6v 750ma battery but i can get sealed, lead-acid batteries, at around 12v and 3amps, but thats still nowhere near what i need. does anyone know where i can get a brushless motor that can have at least 30kg of torque @ at least 1500rpm, that can run off 1A 9V?

Question by oldmanbeefjerky 8 years ago  |  last reply 6 years ago


Casting pewter in RTV Silicone

I want to reproduce a bit of jewellery I have designed in pewter by using a 2-part RTV silicone mould. By all accounts it is possible but I've run into some problems when sourcing materials. Most high temperature silicones I have come across state a maximum temperature of 250°C, But pewter has a melting point of around 280°C. My feeling is that the mould itself will most likely never actually reach 280°C and will probably only be above 250°C for a short period of time. But I'm wondering if anyone has actually done this and could verify for me. Also as I'm new to the whole process, any other tips are welcomed. This is the high temp silicone I'm currently looking at. Thanks,                -Tom

Topic by madmanmoe64 7 years ago  |  last reply 7 years ago


is there a better program i can use with my xbox controller?

im currently using joytokey with my controller  but i cant use the d-pad or a couple other buttons, is there a free program that lets me use all of the buttons?

Question by coldpsyco91 8 years ago


steel cable as a transformer core? Answered

Could i use thick steel cable as a transformer core (1 inch stranded cable) if i saturated it in a nonconductive (epoxy? rubber cement? ect..?   material to eliminate eddy currents and molded it into a double C core?

Question by pwnag3 7 years ago  |  last reply 3 years ago


I have a digital camera with a rechargeable battery. Is there a way to convert to AA, C, D, etc?

My sister is going into the rainforest for a few weeks. She would rather not buy a new camera. Solar-only charging devices seem like a bad idea when you don't know how much direct sunlight (if any) you will see. Is there a way to use her current camera (with a battery that charges off of a wall outlet) but get power from "disposable" batteries (AA, C, D, etc)? What would that be? How do I find it?

Question by 9 years ago  |  last reply 9 years ago


How exactly should an LED circuit be properly set up?

I know LEDs need resistors or else they'll die out really fast. The problem is, I'm having trouble figuring out how this needs to be done. Lets say I take this LED: White 70° Diffused 5mm LED: Luminous Intensity: 690mcd typ. @ 20mA Max Forward Current: 30mA Pulse Current: 100mA for <= 10ms, duty <= 1/10 Forward Voltage: 3.6V typ. 4.0V max @ 20mA Max Reverse Voltage: 5V Power Dissipation: 120mW Operating Temp: -30 to +85 C Soldering Temp: 265 C for 10 secs Max Reverse Current: 50uA @ 5V ok so it has a current of 20mA and a forward voltage of 3.6V. Now, If I wanted to power 6 of these with AA or AAA batteries How many would I need and what ohm resistors would I need? It's been a long time since I took a class on electrical currents, and it was pretty basic. Also, looking at the Reverse Voltage, what is that? Is that if I put the batteries in the opposite direction, i.e. Send the voltage INTO the - and out the + ends? I've been researching this but its hard to find the right answer. Lets say I'm making a basic serial circuit with the batteries here (lined up).

Question by joshka89 8 years ago  |  last reply 8 years ago


Convert DS18B20 temperature to string?

I want to convert DS18B20 temperature (4-bytes code from datasheet) to string with accuracy 0.1°C (like sprintf %.1f). AVR. C language (avr-gcc). I need for small code, so sprintf, floating-point types and round from math.h is bad idea. My following current code is bad also: This is the date sheet of DS18B20 void reverse_string(char *s) {     char *p, c;     for (p = s + strlen(s) - 1; s <= p; ++s, --p) {         c = *p;         *p = *s;         *s = c;     } } void ts_to_string(uint16_t ts, char *s) {     int8_t n = (int8_t)(ts >> 4);     uint8_t neg = n & 0x80;     char *p = s;     float f;     if (neg)         n = -n-1;     do {         *p++ = n % 10 + '0';     } while ((n /= 10) > 0);     if (neg)         *p++ = '-';     *p = '\0';     reverse_string(s);     *p++ = '.';     f = (float)(ts & 0xf) / 16.0;     if (neg)         f = 1.0-f;     *p++ = (char)round(f * 10.0) + '0';     *p = '\0'; }

Question by DELETED_MakiY2 1 year ago  |  last reply 1 year ago


Is there a way to save data onto an ATTINY85 chip, separate from your C program?

Hey everyone, this is my first post and I am not quite sure how to word this, so please bear with me. :) Here is the  ATTINY85 datesheet Basically, the long and short of it is, I made a simple USB HID Programmable Key-stroker Device. I used Macetech's capslocker for inspiration on the circuit design and then wrote my own program in C. Capslocker Design (Basically this design exactly except I have also added two zener diodes for voltage regulation on both USB data lines and a programming header) : http://macetech.com/blog/?q=node/46 However, instead of just sending Capslock on and off (like the Capslocker), this one allows you to send strings of text, combinations of keys, can switch to a mouse and I am currently adding a wireless receiver and RF remote trigger the device with the press of a button to mess with my boss. Currently, if I want to change the keystrokes or mouse movements I have to recompile and then burn the new software onto the ATtiny85 device. Instead, I am looking for an easier way to go about modifying the keystrokes that are saved on the device. Is there anyway to save data to a specific part of the ATTINY that would not require recompiling each time I wanted to update the recorded keystrokes? Or maybe a way to save a text file onto an ATTINY85 device that the C program could load? If not could this be done with an EEPROM? I have programming experience but I am reallllly green when it comes to AVR stuff, so I am not even sure what I should be looking for to accomplish this. Any nudge in the right direction would be appreciated. Thanks for reading and I love this community I have been lurking for quite some time and your posts have helped me quite a bit!

Question by DELETED_MakiY2 1 year ago  |  last reply 1 year ago


Convert 320VDC to 230VAC or 48VDC voltage using 230VAC (UK) UPS?

I've got access to 12 flexible Solar Panels - 320VDC each I live in the UK where mains voltage is 230VAC and also might buy an electric engine which would run at 48VDC. Would a UK voltage (230VAC) UPS be able to step down the 320VDC to either 230VAC or 48VDC for use on a boat? I'm thinking I could connect 12 panels in parallel and use either; Double-conversion UPS to deliver 48V by bypassing the conversion from the battery back to 230V or  Line-interactive UPS to deliver 230V directly from the 320VDC. The question is would the UPS's surge protection be able to deal with the high voltages? (Keeping in mind the sun isn't real bright in the UK). Also with regard efficiency will there be a lot of power loss in the system? I don't really know how surge protection from overvoltage works in UPS's and assume it uses some kind of buck conversion...? I'm guessing that the surge protection circuits might struggle with continued voltage overload. Does anyone know if this would be the case? The question is, will the UPS's be able to reliably deliver either 230VAC or 48VDC? Here are the specs for each individual panel; http://www.innoasia.net/2010/pdf/presentation/SmartCity_Takano.pdf Open circuit voltage(Voc): 429V Optimum power voltage(VMP):319 V Short circuit current(Isc): 0.39A Max operating current(IMP): 0.288A torrence:+_5% Maximum system voltage: 1000V THERMAL CHARACTERISTICS: (-25 ° C to +90 ° C) Temperature coefficient É‘Isc +0.08%/ ° C Temperature coefficient É‘Voc -0.35%/ ° C. Temperature coefficient É‘Pmax -0.15% / ° C. Over-current Protection 30mA

Question by mchin2 5 years ago  |  last reply 2 years ago


How do I create a 5 second soft-start with an LM334Z current regulator?

Hey all, A bit of a newbie to creating circuits I have a 12V battery regulated to 2mA with an LM334Z current regulator. Here are the docs for the current regulator: http://www.ti.com/lit/ds/symlink/lm134.pdf I would like to create a soft start, so that when I turn the device on there is not a rush of current.  I’d like it to ramp up over 5 seconds. I’ve breadboarded a few schematics I found online but I can’t get them working. Even if the battery power is slowly ramped up, the LM334 rams the voltage to get the current at exactly 2mA. (my Rset w/ a 33ohm resistor) Here’s a couple I’ve tried unsuccessfully. http://dl.dropbox.com/u/5822/softstart1.gif (might be b/c the 317 is different?) I even tried this schematic to no avail: http://dl.dropbox.com/u/5822/Screen%20Shot%202012-04-29%20at%209.16.57%20AM.png But I was using different transistors, didn’t think that mattered- let me know if it does Can anyone help me figure this out? I’ve been stumped for days. Starting to pull my hair out :) Thanks Nick

Question by tontoa4 6 years ago  |  last reply 6 years ago


parallel port input?

Plz help me to, how can i receive signal or instruction from paralel port, how should i send current/signal to its register. what equipment should i need. actually i want to develope a system in c language to control electricity of home, doors or widows, so i need to check that if the door is open or closes. when door closed then computer should indicate me that the door is closed, and same door has opened. sir plz give me guideline. i would be very very thankfull to u. ( simply tell me how current/data/signal can be sent through parallel port, current source, equipment ets, after that i will make sensers for it my self)

Question by 9 years ago  |  last reply 9 years ago


is it possible to generate electricity by using a bicycle and an automobiles alternator?

I have been pondering this, and have searched the site but found nothing like this, but maybe using a larger inner tube and putting that around a bare rim and a spindle on an alternator to generate electricity? and would the rpms be enough to generate some charge? and also, it would be a\c charge? maybe it would be possible to charge up an automobile battery, if so it would be pretty neat, and useful.

Question by uLTIMA 9 years ago  |  last reply 9 years ago


how do i add an extra output to my r/c reciever circut board and remote control?

Hi, i was wondering, how do you add an extra output to a r/c reciever circut? what i have is a reciever from a small r/c truck, and im planning on turning it into a tank that requires 3 out puts , not 2 that the reciever has. curently, my controller has 2 levers for making either side of the truck move, both and the truck moves forward 1 and it spins, what i need is a third lever to operate a relay to set off a cannon. what i have currently is a second reciever that opperates on a different frequency to the truck, could i possibly merge the two without using a second controller?

Question by oldmanbeefjerky 8 years ago  |  last reply 8 years ago


8x8x8 Led cube, Parts help?

Ok, Ive been debating this for a long time, and I already bought some of the parts, But Im trying to figure out what else I need. So far, I have" Computer power supply Prototype board from radioshack with copper eyes. Two way screw terminal 3 - 20 pin IC terminals (I know I need more, but 3 is all radioshack had at the time) 2 - 16 Pin IC terminals 1000 uf Capacitor - 6.3v 100 uf capacitor - 10v 33uf capacitor - 6.3v A push button 3 status led's (Red, Green, and yellow) Arduino uno protoboard ^ I also have 18 gauge aluminum wire for the layers.  I have a spool of rosin core solder (I hope this will work, I dont wanna buy more) And Im going to get 1000 blue leds off ebay. with these specs: Color: Blue Size (mm): 5mm Lens Colour: Water Clear Forward Voltage (V): 3.2-3.4V Wave Length(nm): 465-470 Luminous Intensity : 11000 - 12000 MCD Life Rating: 100,000 Hours Viewing Angle: 20-25 Degree Max Power Dissipation : 80mw Max Continuous Forward Current : 30mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V Lead Soldering Temperature : 240°C (<5Sec) Operating Temperature Range : -25°C ~ +85°C Preservative Temperature Range : -30°C ~ +100°C As far as the rest goes I have NO idea what I need. Im going to be using my arduino with it, And im not 100% sure how to change the current instructable here to work with it. they dont specify.  Any help would be really appreciated. Ive wanted to make one for a LONG time :D

Question by 'earl 6 years ago  |  last reply 6 years ago


Can I &quot;upgrade&quot; my Nikko Electric R/C Hummer H2 with a couple of 9 volt batteries without blowing anything?

I have seen a Mod of an Airsoft pistol from Wal-mart that pretty much applied three 9 volt batteries, and it was able to shoot farther and faster and I was wondering if it can be applied to a Nikko Electric R/C Truck the same way. It currently runs on a 9.6 Volt Battery. And I would like to see if there are any precautions or additions I should look into before applying a few 9 volt batteries. Just so I don't blow any circuit boards or anything else. Because like many Americans... we just want everything to go faster. Thank you

Question by 10 years ago  |  last reply 10 years ago


Should I stay with engineering?

I am currently in the 2nd semester of my freshman year of college (University of Northern Iowa) as a physics major. This fall I am planning on transferring to Iowa State for computer engineering but I am starting to have second thoughts. I have always liked learning about technology and building projects (currently robots) and I can't imagine any major other than engineering. I got a C in calculus 1 and physics 1 and am currently taking physics 2 and calculus 2. Physics 2 should be fun (finally get to electricity and circuits) but I am worried about calc 2. I've never been a math genius; does this mean I'm in the wrong major? I guess I am looking for some advice on if I'm in the right major.

Question by Arya42 4 years ago  |  last reply 4 years ago


Anyone know where I could acquire a 120VAC-24VDC converter that outputs ~20A? Answered

Preferably at a price that doesn't break the bank.  I've been thinking about setting up a UPS for a robot that I'm working on, and 20A should be a bit higher than the amount of current that it would draw when up on jacks.

Question by killersquirel11 7 years ago  |  last reply 7 years ago


"Where can I learn Electronics?" ?

People are always asking the same question. How can I tell them the best place without getting cut down for self promotion. (text published by mcgraw hill)? I'm currently working on a set of videos to support the book. They'll  be posted on "instructables" and YouTube. Dave C

Question by Certified Evil Genius 8 years ago  |  last reply 8 years ago


Water Bridge

I was reading this article on how scientist made a bridge out of water, just liquid water, using a high voltage of electricity. They flipped the switch and the water from one glass(well i'm not sure what they put it in, i am assuming a glass beaker) over the very air between the beakers and into the other glass, held up by nothing at all. You won't be driving cars across this thing anytime soon, they biggest they could make it span was 25mm. Supposedly the current restructured the water molecules to create it. I do know they used DC current though. Also the bridge only last for 45 minutes, because of heat, which as the article states, it went from 20(degrees) C to more than 60(degrees)CQuoted from the article,http://www.physorg.com/news110191847.html)Upon investigating the phenomenon, the scientists found that water was being transported from one beaker to another, usually from the anode beaker to the cathode beaker. The cylindrical water bridge, with a diameter of 1-3 mm, could remain intact when the beakers were pulled apart at a distance of up to 25 mm.I'm not sure how much current was going threw them but I would be amazed and appreciate it if someone could find out, experimenting or however they could.

Topic by cd41 9 years ago  |  last reply 8 years ago