Circuits Answered

Can some one give me a clear definition of a transistor.

Question by Dr. Kreap 7 years ago  |  last reply 7 years ago

Circuits and Circuitboards

I would like to make circuits using paper and a conductive ink pen, but there's not way to "attach" the components to the paper. I'm looking for a conductive glue, like epoxy or super-glue, I can apply directly to the point of contact between the paper and the component. Can anyone suggest a product, or how to make such an item? Thanks, Kevin

Topic by kevin.t.stein.3 1 year ago

circuit board

 Hi guys, I am looking for a high quality circuit board manufacturing  that can deliver high quality  circuit board ASAP and with fairly reasonable cost .  any suggestion?

Topic by Michael2000 3 years ago  |  last reply 3 years ago

Switching Circuit

Hi, I want to build a Auto-Switching circuit. I would appreciate if you could help me on circuit. Sorry for my ignorance in circuit design. There are two power sources A and B. The A is 12v and B is 3v.I would be utilizing the power from A only when B is turned On. So an auto switching circuit is required in this scenario. The circuit should sense if B is On, if so it should let A On.

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

Pulse circuit?

I need to make the circuit that every time it charges the capacitor to a certain voltage (e.g. 5v or 12v) it discharges it

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

Circuit boards

Does anyone know where I can find replacement circuit boards for my Gateway model number vg70 laptop

Question by CarletonG 21 days ago  |  last reply 21 days ago

Circuit Timer

I would like to be able to set a time, small like .5 seconds, and be able to power a 12v circuit for that amount of time, any ideas? 

Topic by ReconIII 5 years ago  |  last reply 5 years ago

Circuit tracer???

Can anyone tell me how to make a device that can scan and trace an entire electronic pcb and give a schematic result ???

Question by 10sicnarf 4 years ago  |  last reply 4 years ago

Circuit Problem? Answered

Hey guys i just made this circuit ( pic provided ), The problem is when i  clap the led that indicates the circuit is off turns off (power goes to the relay coil) but  the circuit off indicator led turns back on after a few sec and the relay does turn on at all. (Yes the relay works) And another thing I observed is that when i take the coil wires off and attach them to an led instead of relay it works correctly and the led stays on till i clap again to turn the circuit off.

Question by SA-DIY 3 years ago  |  last reply 3 years ago

Charging Circuit

I was wondering if anyone had any ideas on how to make a circuit so that I could charge a battery, but that I can also power an amplifier when the battery is not charging. Currently I have a switch that switches between a charging circuit and powering the amplifier, but I was looking for a way to do this without having a switch that I have to control

Topic by Fozzibehr 5 years ago  |  last reply 5 years ago

Circuit design

Hi, I’m hoping someone could help me. I’m looking to design a circuit for a college project that controls a 240v light. The circuit and light will be controlled by a switch however when the switch is first turned on the light needs to remain off (no power supplied) regardless of the amount of time the switch is on. If however the switch was turned on off and on again then the light needs to come on. Any ideas of a circuit and components required to produce something like this? Your help is greatly appreciated.

Topic by Worby10 4 months ago  |  last reply 4 months ago

Protector Circuit?

How can I make a circuit that will protect an LED when I plug it into a traditional light bulb plug?  hint- homemade LED light bulbs.  

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

inverter circuit

I have several BD139 transistors, several types of transformers, blocker diodes and 40pf 50v capacitors. can anyone show me a simple schematic to convert low voltage to high voltage?

Topic by buddybro 5 years ago  |  last reply 5 years ago

door circuit?

When door open led on when close led off for 5 doors windows etc.. display led on one mainboard

Question by fawzi 9 years ago

Circuit not working...

So I made this circuit ( but it doesn't seem to be working. When I connect it to power the relay is in on position and the led is off. No matter how many times i clap it doesn't seem to change state. Can anyone please tell me what i could've done wrong? Note: when i touch the bottom of the circuit ( on some pins between 1 and 4 of ic 741) it seems to change state. Help would be greatly appreciated thanks. (This video: shows this circuit in action. It seems that he used an LED instead of a relay. I also found similar circuits here:

Question by SA-DIY 2 years ago  |  last reply 2 years ago

Circuit not working?

Hey Guys, This is like the 5th question regarding the same circuit. Maybe its because the circuit is a bit hard to make or .. idk. Anyway I tried it on breadboard and in the 5th attempt it worked but now that i soldered it on the normal perfboard its not working. It doesn't detect the clap at all.(the microphone is properly connected).I dont know what I did wrong. I bought a multimetre recently so if you could tell where im supposed to see what voltage that should make it easier to troubleshoot the circuit. BTW Pin 12 and 13 are not connected because i remember when they were connected on beadboard it wasnt working.

Question by SA-DIY 3 years ago  |  last reply 3 years ago

Circuit not working? Answered

Hey Guys, a few weeks back I posted a question about a clap switch with an IC 4017 not working (relay not turning on). Well I tried to make the project again. The problem is now the relay wont turn off (-_-). ( video of the project by another guy ( He doesn't use relay, instead he uses an LED. The problem with mine is that when I give it power the CIRCUIT OFF LED is off and the relay is on, indication that the circuit is in on position, so far so good. But when i clap the CIRCUIT OFF LED turns on indicating that the circuit is off but the relay stays on. The first time I tried, i didnt put the diode near the relay, same result. THen I put a diode (the wrong way), nearly burnt my hand. This time i put the diode in the same way that im supposed to but the circuit still has the same result. I have uploaded the schematics, Hope someone can help me. UPDATE: I was using MJE13003B instead of BC547. When I was using the mje13003b it was very easy to turn the circuit on and it used to come on at first try. When i inserted the BC547 the circuit was in off position I clapped and it worked like a charm the indicator led turned off and the relay turned on. But when I tried to turn it back off, everytime i clapped the status led blinked and thats it, It just blinked, the circuit would be still in on position. I wonder whats the prob since turning it on is easy and turning it off is impossible. NOTE: Now its the same with the on position. Whether its in on or off position same thing happens. In one of the million clap it turns on. Thanks in advance. -Prickly Potato

Question by SA-DIY 3 years ago  |  last reply 3 years ago

Circuit Help!

Hi, I'm trying to put together a basic circuit for charging a capacitor/s with a built in LED to indicate when it's charged. I've created a draft on Multism but can't seem to get it to work. I'm a complete novice at electronics and have pieced it together from various schematics I've found. Help please! :)

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

circuit imprime

Bonjour ,j'ai un ecran plat qui marche 5 s et apres plus l'ai demonte .allimente plus rien ,ni image ni voyant power.

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

Circuit not working? Answered

Hey Guys I just made this circuit (schematics provided) and it doesn't work. The problem is that the  at the output of the 2N3906 transistor the voltage is only 0.5-0.7. So that isn't powering anything. I was wondering if anyone could tell me what the problem is. (the first pic is the original and the second one is the modified one with i built). Thanks in advance. -Prickly Potato

Question by SA-DIY 3 years ago  |  last reply 3 years ago


Hi would this work if i used 5 12v Leds(parallel) and connected 3 9v pp3 batteries(parallel) for power, also would the LEDS need there own resistors each? look at image for detail

Question by jbutcher05 10 years ago  |  last reply 8 years ago

Blinker Circuit

Hi i am looking for a good model for a turn signal circuit. i am trying to make turn signals for my mower (not a joke) and i need a list of parts i need to buy, and a image of the circuit i already have the lights and switches. i would like to have it so a switch is for each side, and   i would also like it to be able to do hazard lights, i dont know if i would be able to do that by switching both switches on at the same time?. but what ever you got to help me would be awesome. thank you

Topic by RC Instructables 6 years ago  |  last reply 6 years ago

Will this circuit work? Answered

It works, but are there any problems with it that might fry the chip or something? Also, I didn't know if audio ground should be connected directly to the amp ground, and I saw one schematic that had a 10K resistor in between so I just did that.

Question by 7654321 8 years ago  |  last reply 8 years ago

Circuit Help

Hi, i saw a video by the king of Random He hand cranks up a drill to charge a phone.. but what i wanna do is similar but different, instead of charging a phone i want to charge a battery and what i need to know is, what component do i need to stop the current from the battery to go back into the drill once i stop cranking so it doesn't depletes..  

Topic by Arghus 4 years ago  |  last reply 4 years ago

Electronic Circuit

I have a spst relay(operating voltage-12v) using for switching the solenoid valve(24VDC and 0.5Amp) which connected through 24 V battery. relay is again connected to the transistor BJT NPN . So please suggest me that which transistor is most suitable.

Topic by jay_3189 5 years ago  |  last reply 5 years ago

Sound Circuit

What I want to do is set up a switch so that every time it is toggled, one of two sounds are played on a speaker (which I also don't know how to connect). How would I go about doing this? This is for a homemade Aperture Science Handheld Dual Portal Device.

Topic by elementcollector1 7 years ago

circuit board

I need to make a circuit board for a project. It is all 12vdc, I have a 1a fan and a 6a thermoelectric device one setting 1, plus another 6a on setting 2, and a 3rd on setting 3 So 1 is 7a 2 is 13a 3 is 19a How to make the board. Also a second device has the 1a fan plus a 4watt element, plus another 4w on setting 2, plus another 4w on setting 3 So 1 is 1a and I think 0.4a= 1.4a 2 is 1.8a 3 is 2.2a. I think

Topic by Johnieahenderson 2 years ago  |  last reply 2 years ago

Will this circuit work?

Ok, so I'm building a giant led array and I'm running it off of a PWM chip and a few shift registers. Given the number of addresses and variables I need for each one, I'm guessing that the micro running the show won't like that too much and will be a bit slower than I'd like, and i'm not sure if it will be slow enough to cause irritating visual inconsistencies. This got me thinking, how did tube TVs do it? They had phosphors that slowly released their charge and therefor looked alright. Thats how I arrived at this circuit. Will it pretend to be a phosphor well enough or will it need something different?

Question by The Ideanator 6 years ago  |  last reply 6 years ago

Timer Circuit

I found this simple circiut on, and was wondering if and how to change it so that it could time in the minutes, longer than it does already. I don't know anything about electronics, aside from soldering, and basic connections, so try to give a simple-ish answer. I also wondered about what transistor to use (like a radioshack part number). The circuit I was talking about is under "discrete timers".(update, more questions)What kind of timing (like how many seconds) would I get with this?Using the same stuff shown on the schematic?Also, how do I pick a transistor?Are they interchangeable? What specs should I be looking for? If this seems like too much, could someone give me a link to a site that would be willing to help with (very) beginning electronics?AND, how would you recommend making the transfer schematics for home-etched circuit boards? I can't get the component spacing right.

Topic by John Smith 11 years ago  |  last reply 4 years ago

Theremin Circuit?

Does anybody have a theremin circuit that doesn't have coils? I need it to be compact so programming seems ideal. A PIC solution might work...any suggestions? Any other processor is fine also. No, I can't use a light theremin... And no, I can't use Harrison Instruments' because its too big and too many connections. If possible, then this is to be used on fruit flies to see how much activity they do when foreign substances are added. Again, if possible if a PIC solution is used, then can the PIC detect when the flies move because they change an oscillation. Most likely I will wind a coil and place it in the jar and then have it detect. The best way would be to use the PIC to print an output via some sort of display so that the scientific results can be tested.

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

Of solder and circuits

To dodge an onslaught of summer boredom, I'd like to fart around with small scale electronics projects (LEDs, maybe a circuit board, etc.). I hope that by the time I finish farting around, I would have something nifty to post on this website. Unfortunately, I have little practical knowledge of this stuff (other than what I learned five years ago in high school electronics). I mean, I don't even know how one technically refers to "this stuff." Can anyone recommend some good books or a general method of wetting one's feet before jumping into the pond? Highly technical sources are obviously beyond me at this point, so I'm looking for introductory-level information that can be flexibly applied to whatever bizarre project pops into my mind on Friday afternoon.

Topic by ringtail.jack 11 years ago  |  last reply 11 years ago

LED circuit?

I recently purchased a few LEDs for a project, 2 blues and four reds. I need a way to power them all for months at a time. Would a nice soul be kind enough to draw up a schematic for me, considering I know NOTHING about this stuff? Here are the schematics, taken right off the back of the packets. 4 Red LEDs: Forward Current: 28mA max Forward Voltage 2.6 V max 2 Blue LEDs Forward (supply) Voltage: 3.7 typical, 4.5 Max Forward (supply) current: 20mA typical, 30mA max Any help?

Question by Rotten194 9 years ago  |  last reply 7 years ago

Soundcard Circuit

I've been looking for a soundcard that will work for what I need for a project I'm working on. I need about 6 inputs I prefer to make it myself, just to make it more fun and challenging :) I don't have much experience with this kind of thing so I need some help. I can't seem to find the information I need by myself so here I am asking for assistance. The texas instrument pcm2900 chip that is used... Do I need 6 of them for 6 inputs? I need them to be completly separate.  He says he is running 2 inputs off of this chip. I guess the 2 inputs share the converter? When I get to programming I need to have 6 separate data streams (one for each input) Thanks in advance for all advice!

Topic by amplifihip 6 years ago

Charger circuit

Hey there, I'm planning to build a portable stereo speaker box thingy (you know what I mean). In order to power the 2x10W amplifier I want to use a 7.2V 1400mAh battery pack from an old RC car. As the housing of the box will be sealed I want to implement a mechanism to charge the pack. For this I wanted to achieve 3 things: -If the Power-Switch is turned on, the amp should be powered from the power line -If the Charge-Switch is turned on, the battery pack should be charged -If both of the switches are turned on, the amp should receive power from the power line while the battery pack is being charged. I have thought of the following cabling (see attached picture for a schematic) The blue box is the amplifier, the green box the battery pack and the orange connectors are tamiya connectors (the ones for RC cars) The first switch (marked in green) is a normal DPST switch which establishes the connection with the power line as well as the connection with the battery The second switch is a SPDT switch and activates either the connection between the battery and the amp or the connection between the power line and the battery. Will this work the way I think it will or does this configuration any faults? If the latter, what can I do I have to change? I'm actually really new to electronics, this if my first project so forgive me, if this setup is actually BS Cheers and sorry for the long post ^^'

Topic by Felixkeeg 3 years ago  |  last reply 3 years ago

Circuit help

So, my brother tasked me with making him a customizable doorbell for his house for Christmas (of course he didn't tell me till last week, but whatever). looked around at a bunch of stuff online and found a few decent items. some of them use those voice recorder modules from radio shack...which  might work, but I've used them before and they're pretty quiet. also, not the best sound in general from the mic used to record to them. so I found this thing;=1 which is a riff on this thing  which uses an ATTINY85 to play audio via the PWM output from an SD card. I like this guy because it's gives more options for sound and is generally more "gee whiz". however, the guy built it from scrap parts and has some admitted flaws in it, notably the power supply and the audio amplifier. so, I'd like some help figuring out how to build the same thing, but with a more "correct" power supply and amplifier. also, not exactly an electronics wizard so the fact that there are a billion different chips listed as ATTINY85, I wouldn't mind if someone can make a more sensible parts list (there aren't that many parts). I plan to trigger the thing with an off the shelf wireless doorbell type thing.

Topic by crapflinger 3 years ago  |  last reply 3 years ago

(SOLVED) Break circuit = Make circuit?

Basically, what I want to do is activate something when there is no current somewhere else. Examples of uses of this would include turning an LED on when there is no light on an LDR and turning it off when there is light, rather than the other way around, along with turning an LED on when a circuit is broken by opening a door. Apologies if I have not been clear enough. Is this possible?  EDIT: Thanks to NachoMahma, I have it set up with a transistor. I will post a schematic if anyone is interested.

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

circuit building and designing?

Hello i am new to electronics i want to know how to design/design a schematics a specific  circuit i means where to place resistor ,cap,and other electronics  i have perfect idea about most of basic electronic component but can any one suggest a method to build own circuit or scematics?

Question by mihir.sahu.355 3 years ago  |  last reply 3 years ago

DC to AC Converter Circuit

Hi, so I have a sound amplifier that is designed to run off of 18-28V AC power, but I want to try and run it off a 24V Battery, can anyone give me a circuit that would achieve this?

Topic by Fozzibehr 4 years ago  |  last reply 4 years ago

Completing a circuit when a circuit is broken

I'm wondering how a circuit is made similar to an alarm. For example, when a point in a circuit is broken, it activates something else (led, etc.$

Topic by cyberguy91 6 years ago  |  last reply 6 years ago

I need help copying this circuit. Answered

I need help copying this circuit so that i can experiment with it using microphones and speakers and cameras and screens. If somebody could identify the components that would be magnificent. i just need to know whats on there so i can copy it. I mostly need to know what those black things are.

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

what is involved in a photoelectric counter circuit?

(just turning on and off a light to make a counter tick each time the light comes on)

Question by 10 years ago  |  last reply 10 years ago

Is a series circuit with 12.08V and a 150 Ohm Quarter-Watt resistor safe?

I have a series circuit with 12.08V from a DC power source running through it. There is only one quarter-watt resistor at 150 Ohms. Is the circuit considered safe and why?

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

how to make a circiut that senses and responds to megnetic fields? Answered

I need to make a circuit to power an overunity generater

Question by nerd7473 7 years ago  |  last reply 7 years ago

I want to make power supply from 220 V AC to 300 V DC variable/adjustable?

I want to make power supply from 220 V AC to 300 V DC variable/adjustable? someone please help me or give me a link of workable circuit?

Question by innocentkhalil 5 years ago  |  last reply 5 years ago

How does a Tilt Swith Work?

I am looking to make something which a group of Cub/Scouts could use while working together as a team. eg::- a Small circuit board that has a Tilt Switch / Motion Sensor on it which triggers a Audit and Visual alarm to let them and others know they have moved it. Please help Cheers Sandy Cubs Scout leader with no knowledge of this subject

Question by Sandy1Taylor 10 years ago  |  last reply 10 years ago

how to power a starship coil?

I want to power a starship coil that i built

Question by nerd7473 7 years ago  |  last reply 6 years ago

My battery pack keeps melting?

I am making a simple circuit with only batteries and LED strips - I know it must be shorting but very new to this and wondering how I can find the short and fix it? It takes around 4 minutes to melt the pack, I am using 8 AA batteries as was told the LED strips work at 12V.  Would really like your help.

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

How do I wire (1) 9v motor and (1) 12v LED strip to one momentary switch using 2 batteries?

My project entails the push of a momentary switch to turn a 9v hobby motor and also light a 3 bulb strip of 12v LED's.... all using 2 different 9v batteries.  I'm concerned that one 9v battery will not last long so thought 2 batteries would be better.... one for the motor and one for the LED strip.  I'm just not clear on how to wire the motor and LED's to the switch.  I assume the positive battery wires go the switch and then to each of the respective units (motor and LED strip)  Just not sure if this could cause things to heat up since both battery leads would go to the same side of the switch  Many thanks and hope all this makes since.  .   

Question by sequoia4me 3 years ago  |  last reply 3 years ago

Circuit with Thermistor and buzzer?

How do I build a simple ciruit that will cause a buzzing sound when the temperature rapidily increases?

Question by Emmsie 8 years ago  |  last reply 7 years ago