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designing and building power supply using pre amplifier and darlington transistors

am doing a project on building a power amplifier driven by a pre amplifier with normal darlington complementary power transistors for school and i have no idea of where to start with.HELP PLEASE sandra

Topic by sandy23    |  last reply


Anyone know how to build a device that says a pre-recorded message whenever there is power going through it?

Just going to use a simple wall timer so I can make it go off when I want, Im guessing it would just be a recording message device from radio shack and it says the message when you put power into it, does anyone know how to do that. Much appreciated if someone could draw up some schematics for me, Thanks.

Question by Itscrafty    |  last reply


pre-school games?

I'm looking for gross-motor games for pre-schoolers?

Question    |  last reply


Pre-drilled shelves?

I would like to know where I can purchase the pre-drilled melemine shelving upright boards in order to construct some custom built bookcases.

Question by masterhog    |  last reply


Do pre-programmed PICs exist?

I'm trying to complete an instructable however I ran across a small problem: I need to program a PIC. Unfortunately, the devices used to program the PICs (Pickit2) are too expensive for something that I'll use maybe once or twice. Is there a way to buy pre-programmed PICs with custom code? Thanks. 

Question by Rolcrz    |  last reply


Pre-peeled versus fresh garlic?

In what dishes can you tell the difference between pre-peeled and fresh garlic. How about Chinese versus Californian pre-peeled garlic?If you can tell the difference, how can you be sure? I love garlic, and use a lot of it. I'll toss a handful of chopped cloves into almost any savory dish that involves a sauteing step. Using so much and being pressed for time, I primarily buy Californian pre-peeled garlic, and chop it right before I use it. I'm curious if you judge pre-peeled garlic to be less flavorful, and if so, can that flavor be returned by an increase in total garlic or if there are fleeting compounds that escape as soon as the garlic is peeled.Another thing I've noticed is that I need to be careful when I make dishes where I food-process the garlic to mince it. I've ruined a curry or two by using food-processed fresh turmeric, fresh peppers, and pre-peeled garlic that smelled fine but had probably spent a week in the fridge. In the finished dish, the garlic contributed a pretty nasty "raw vegetal" taste. Similarly, Christy once food-processed and sauteed some onions and older pre-peeled garlic only to have the whole mixture turn blue and taste horrible. http://whatscookingamerica.net/Q-A/bluegarlic.htmThe discoloration is due to pigments that form between sulfur compounds in garlic and amino acids. When the garlic tissue is disrupted, as happens in processing, an enzyme is liberated and reacts with it to form thiosulfinates compounds that then react with the natural amino acids in the garlic to form blue pigments. The age of garlic determines how much isoalliin there is in the first place, and the nature of the processing determines how much enzyme is liberated.The blue color apparently shouldn't harm the taste, so it would be neat to develop a dish that naturally turned blue using this reaction while still tasting great.

Topic by ewilhelm    |  last reply


Need pre wired high power leds

I am in need of a pre wired High Power Led board. Something like a Cree XR-E Q2 Emitter. I would like to find a supplier that I could buy pre built/ wired boards (plug and play) to install in a small lighting package. Ideally I would like to find a pre built light that I could incorporate into my project. I need a high output 12v white light, that I can make a reverse light out of. I am hoping to market the product so a supplier over a retail option would be best. Any help you could give would be greatly appreciated Thanks in advance  

Topic by returnforservice  


Is it possible to create a pdf of draft Instructable, prior to publishing?

Hello - Another group is reviewing my Instructable prior to publishing.  I sought their permission to use some of their reference material.  They have asked if they could review the Instructable in a pdf format.  It seems like you can only produce a pdf after it is published.  Is there are pre-publishing method?  Thanks, dorybob

Topic by dorybob    |  last reply


help to remember what im doing

The pic says it all lol. i can remember for the life of me where i am to solder the bass pickups to and where the out put goes to lol. ANY HELP PLEASE *begs on floor kissing feet*

Topic by joypad    |  last reply


how to stay connected?

My t-mobile acct. has been disconnected.But with my husband in Icu I kinda need my phone.If  I buy a prepaid sim card can I still use my T-mobile phone?Desperate in Fl.

Question by miamihomegrl    |  last reply


Well Filter

Hi there, I need a water filter for my well, which i can hook up before the water riches the pressure tank. I got a lot sediment in the well. I was thinking of a filter like from a fish tank. My Idea is , i fill it with gravel from big to fein (Sand) gravel in at least a 6 inch pipe and about 4 feet long. The pump company ( Flotec) told me that i need a pipe with min. 100psi rating. I want use a clear pipe so i can see when i have to change (clean) the gravel.It should also be mounted in the basement ( freeze protection). I found on the i-net a clear pipe with treats on the top and bottom, but than it's not rated any more for 100 psi. so what can i do. Any clue?

Topic by germanudo    |  last reply


help! modifications on a vintage pre-amp Answered

I found a working pre-amp inside a turntable from the 60's. The turntable was scrapt, so I remove the pre-amp from inside. Now I want to put it inside a vintage radio wooden box, the problem I got, 5 potentiometers on the pre-amp, but I need to modify this so it will only have 2, becuz the radio box has only 2. I will use an iPad with this pre-amp, so there really no need for extra audio adjustments like treble or bass... So one for volume, the other for open and close. How do I modify the circuit of this pre-amp so there will be no sound problem ? Do I remplace the gradable resistors with a standard value resistor, if this is how to do it, what value should I use ? I've done some tests, if I skip the potentiometer and I'm getting too much static. I' would appreciate help on this! thank everyone !

Question by sebdub    |  last reply


Want to know how to build a waste oil pre-heater for a waste oil burning furnace.

Who out there can tell me how to build an oil pre-heater for a waste oil burning furnace. I need to heat the oil so that it will atomize through a Carlyle AF 15 oil burner. Any help would be appreciated.

Topic by rattle09    |  last reply


Pre-Formatted Text Issues

Hello; Several of our instructables have pre-formatted text in them. However recently this text has stopped displayed properly. It has gone from being multiple lines to a single long line. Is this a fixable issue? Examples: https://www.instructables.com/id/S99CDK8FWS6JUQS/ https://www.instructables.com/id/SAXXIILFSH7EDVM/ The Long line after "The Code"

Topic by oomlout    |  last reply


Call for pre-made parts!

We're rolling out some new parts for the Kits in 123D Design.  That means you'll soon have some real-world models at your disposal in the Design app, and I wanted to see if there were some specific requests out there for parts that you might use on the regular. I've put in for some tools and hardware - like metric and SAE wrenches and hex bolts - but is there anything that you'd like to see as a part or a template?   M4 screws for an Arduino enclosure? 4" 2-way gate hinges? Eye-Hooks? Light bulbs? Threaded rod? Phone cases?

Topic by andrewt    |  last reply


How do you get a shipping container certified to legally live in?

It would be cool to attach a bunch of those things together and install a bunch of doors, windows, decks, etc. Seattle, Washington

Question by sensoryhouse    |  last reply


please help me! record player question! need help setting up!

ok i just got a record player,some records, and a pyle p999 phono preamp for christmas. the output is a red and white cord. is there any way to listen to it without getting a amplifier?

Question by madrobot3600    |  last reply


Arduino LM386 Pre-Amp for Mic ?

I am trying to (pre) amplify the signal from an electret microphone using an LM386. The output goes into the Arduino analog input 5. I have tried multiple circuits, but none of them succeeded. Either the value settles at some constant or its 0/1023 and even when its in the 500- 550 range, the value doesn't seem to be changing with varying sound levels. I tried these circuits: http://wiring.org.co/learning/basics/microphone.html https://randomskk.net/projects/lightstrip/schematic.pdf http://www.josepino.com/circuits/mini_amplifier_lm386 http://www.diyaudio.com/forums/chip-amps/114698-preamp-using-lm386.html and a couple of more ones. I only have an LM386 on hand and cannot change it, as I need this to work out ASAP(in 2 days) for a science fair project. Hope you guys can help me on this. Kabir

Question by mhkabir    |  last reply


Pre set voltage regulator/supply

Hi I want to modify the DC to DC buck circuit that is sold anywhere, to have pre-set voltage by pressing only one button it will set at 3, 5,9 and 12 output

Question by nickp238  


any ideas for an old palm pre?

Found one with the orig. packaging about to be tossed.  I figure there must be some good ideas out there; i wanted it originally to be turned into a pay as you go for my kids or as a back up as i crack a few screens.  Any ideas?  Please dont snark.

Question by GlanternJay    |  last reply


Looking for pre-printed circuit boards

I've been looking around the web trying to find a place that sells ready made circuit boards, plated and pre-drilled; like what you would find in Radio Shack but with a larger selection. I've looked at Mouser and their selection is rather limited. What I need is a circuit board about 1" square for mounting tactile buttons on it.  Like I said I've been looking all over and all I can find are websites that make custom circuit boards, but nothing already made. So anyone know of a place where I can buy already made circuit boards?

Topic by wickednick    |  last reply


Gameboy Mintyboost Solar ???? You tell me

First off, I'm a noob, but so far I have learned a lot. I have made the mintyboost with the solar ipod charger mod, but I had to put it in something different that a mint can. So naturally I went back to my roots and thought of the old school gameboy. So my ??? for you the educated and creative community is what else can I put in this case for fun?  On the front are 8 possible switches I could use to turn on/off led lights, mp3player, spy camera, taser, simon says, etc I just wanted your ideas on what you would put in. Thanks!

Topic by 007onionrings    |  last reply


Good pranks to play while trick or treating?

I need one within three days so I can plan it need some ASAP

Question by Poprockzftw    |  last reply


Permanent screening for a pre-fab metal gazebo

I have a metal outdoor gazebo and am tired of the flimsy hanging screens supplied for it. How do I install permanent screening around it? Can I attach screening to the metal frame? How? I will continue to use the removeable canvas top. Installing doors is not an issue as I will leave "floating" mesh panels at each end for that.

Question  


Pre-historic Video Amplifier Antennas useless?!

I've been learning quite a bit about video amplifiers recently. And it's brought me to a question. When antennas were the source of video-signal, you would often hear horror stories of people having to get up off of their couch to adjust the "bunny ears", to get a clearer signal. I'm just confused. Why would they have to be adjusted? The signals, if my understanding is correct, is electrical signals sent through the air, and the signal would cover thousands of feet. It surely didn't matter if the antenna was all but a few inches from one spot or another. The signal should be able to hit it just the same no matter what, correct? If you are in a car, it's one thing - you're moving. But in a house, you're stationary. Any explanation?

Topic by freethetech    |  last reply


Cheap Simple Pre-Loaded Sim Card? Answered

So I am looking at making some GPS/GSM trackers which are attached to a vehicle and then used in the case of theft.  They would be powered by the car's electrical and would also have a separate backup battery in case the thieves were smart and disconnected the electronics.  The only problem I have seen in planning is the requirement for a sim card on GSM modules.  I understand that I will be required to pay for service, but I need long range, maybe even international service which can send maybe 20 text messages at most.  A pay as you go would be reasonable too.  I just don't want to pay a monthly fee for a fake phone which just sits on a car doing nothing most of the time and doesn't actually do anything until it is called or texted.  Any car trackers I have found don't offer wireless capabilities and I really think my device would be useful.  

Question by jj.inc    |  last reply



Heating a winter garden pond with a car pre-heater!?

Anybody thought about heating a winter garden pond with a car pre- heater!? Here in the UK garden pond fish get really cold and more often than not ponds freeze up. Would you budding geniuses give this topic a little thought - would it work in a controllable manner?Thank you.

Question by TN1946    |  last reply


Electret mic and lead for odd voltage pre amp

Hi.I want to make an electret mic and lead into a 1/4 " jack for a phantom powered pre amp. The pre has a low output voltage of approx 6 or 7 volts not the usual 48.Do i need to add the usual capacitors n whatnot??Its a rare old beast from the 80's n i cant locate specs on it n dnt really wanna open it up.Thanks in advance.

Question by Squiza    |  last reply


How to measure pre-shirred material for a summer dress?

I am new to making clothes and am self taught on my sewing machine. I bought this really cute cherry pre-shirred material, and am trying to figure out how to measure it to fit my body right. Is there a special way I need to do this, or is the answer right under my nose and its passing me by? Any adivce would be greatly appriciate. So, again, my question is, How to I measure the pre-shirred material to make my summer dress?

Question    |  last reply


Larger K-nex like parts for pre-K

I just discovered that the K-nex like building set I have isn't K-nex!  The pieces I have are larger and are made of a softer material.  They work well for children in the 2-5 yo range.  Would anyone know what these pieces are called?   The 1000 pieces of K-nex are going to have to wait a few years..... Thank you in advance.

Topic by brainfog    |  last reply


Tall irrigated hedge to pre-cool A/C condenser? Answered

I am thinking about planting a hedge around our air conditioner condenser to increase its efficiency. This would serve as shade for the condenser and as a means to inject water to keep the plant cooling the air as it evaporates the water. When rainwater is available, an aquarium pump could "irrigate" the hedge. When not available, a switch could control a valve for a high-pressure drip irrigation system. Both could be controlled by the compressor circuit. Keep the hedge trimmed about 6 feet tall and with just enough space around the condenser for a workman to easily maintain the unit (at least 3 feet from the condenser). The hedge would have to be drought resistant and one that does not shed leaves or debris. Any thoughts about this?

Question by VirgilB6    |  last reply


2013 Pre-Maker Faire Ice Cream Social!

In town for the Bay Area Maker Faire next weekend?  Come to our annual Liquid Nitrogen Ice Cream Social! There will be: Liquid nitrogen Ice cream made with liquid nitrogen Pizza (not made with liquid nitrogen) Beverages (possibly made with liquid nitrogen) Authors and other interesting people (playing with liquid nitrogen) Also, we may have some liquid nitrogen When:  5-8pm, Thursday, May 16, 2013  Where:  Instructables HQ, 82 2nd St, SF, CA (look for the big robot on the window!) Come see our lab, meet some amazing people, eat pizza and ice cream, meet the Instructables team, and take advantage of your last chance to really decompress before the craziness that is Maker Faire. If you can make it, please RSVP to: LN2 @ (instructables.com)     <-- slightly obfuscated to avoid spambots! so I can order enough pizza for the crowd!   We're looking forward to meeting you! Christy and the rest of the Instructables team

Topic by canida    |  last reply





What are some good arts and crafts for a pre-k class?????

I work with my moms summer pre-k class and i want to know good arts and crafts to do with them somethimg easy and u dont have to spend so much money on any materials.

Question by EmmettCullenrocks    |  last reply


What do i need to do 2 be a pre member?

What do i have 2 do 4 a pro membership? is it free? What does it do?

Topic by hobo8675309    |  last reply


Whay arent yo watching the Superbowl, pre game, and hype?

 I can't stand football. I'd much rather be here, with the exception of the commercials, of course. So, as I hear the hype, pre game, and other nonsense going on in the back ground, I'd rather surf around and goof on the computer.   What about you?  Feel free to post any nonsense or general gripes on the sport. Such as: Its a brutal sport that people get paid to risk mind, body, and spirit on with little other than monetary gain and a brief shot at fame.

Topic by onrust    |  last reply


Instructables' Annual Pre-Maker Faire Ice Cream Social!

It's that time of year again! In the spirit of Maker Faire and all things DIY, Instructables is hosting our annual Pre-Maker Faire Ice Cream Social - and you're invited! We want to thank our awesome community of authors for sharing all the cool stuff they're making, and for helping us grow our site to 75k projects! We will be hosting this free ice cream social at our downtown San Francisco headquarters for all our authors and maker friends. Come meet the team behind Instructables and get an inside peek at our lab. In addition to some frozen Liquid Nitrogen ice cream treats and adult-beverage popsicles, we will be holding a "Show & Tell." Bring along a small project of yours to show off! And, just in case you're not already going, we'll be raffling off a select number of tickets to the Bay Area Maker Faire. So please come join us! RSVP in the comments below When: Thursday, May 17 4-9 pm Where: 82 2nd Street, San Francisco Looking forward to meeting you, Karen and the rest of the Instructables Team

Topic by kazmataz    |  last reply


Friday Forum: Ask an Editor (pre-Maker Faire edition)

Hi guys. My name is Wade, and I run the editorial team at Instructables. I'll be answering community questions posed on this thread on Friday, May 16th from 1-4PM PST.   All questions asked and answered for today. Feel free to ask more questions, though, and we'll probably run another one of these in a week or two. If you've been curious about the site, here's a chance to get the inside scoop on what actually goes on at Instructables. how to get featured how we choose featured authors the best time to enter a contest how much meat do Eric and Christy actually consume? how we decide what prizes to give away ...and whatever else you're curious about Thanks to everyone who participated. Especially Ben, whose interrogative greed was beneficial for everyone who lurked without posing a question. For the next Friday Forum on May 30th: https://www.instructables.com/community/Friday-Forum-Ask-an-Editor-Contest-Edition/

Topic by wilgubeast    |  last reply



how do i put a verizon pre paid card on my at?

Purchased a prepaid verizon phone card plus want to use it on my at&t go phone

Question by d1963    |  last reply


Passive subwoofer and receiver with "subwoofer pre out" plug in harman kardon avr 142

Hello, I have Harman kardon avr 142 with subwoofer pre out plug in (suitable for active sub), and passive pioneer subwoofer with two cords. Between them I have rg59 with rca head (sub cable). Is there a way some how to convert the pioneer sub to an active sub with rca plug in?

Question by BarD2    |  last reply


How to make my dynamic mic pre-amplifier circuit work? Answered

Hello everyone, recently I'm making a sound box that have a sub-woofer sound system that works pretty fine, but for my usage I need to add a dynamic mic input which needs a pre-amp. before sending the mic signal to the sub. aux. I found this circuit and tried to apply it, I didn't get anything at all, but the surprising thing that when I connected an electret mic, it worked like a charm ! So, what is the problem I'm missing ! if anyone have any Ideas or better circuits for my purpose please feel free to give any ideas, thanks :) Note : even the electret mic didn't work before I canceled the capacitor after the mic input, I'm using uA-741NC @ 12V.

Question by Hawk-Eagle    |  last reply


Comment post-processing does not respect line breaks in PRE-blocks

I have just noticed that the post-processing done when a comment is posted does not respect line breaks included inside ... blocks.  See, for example, my reply to https://www.instructables.com/answers/How-do-I-include-code-in-my-instructable-and-not-h/.  The preformatted text is shown as a single line, but entered it as three lines:   The text seen here   is in fixed format,   sort of like source code. Notice the line breaks, which are respected when I type stuff like the above in the WYSIWYG box (so the tags get converted to &lt;/&gt; entities).  Here is exactly the same five lines of text entry pasted into the Source interface: The text seen here is in fixed format, sort of like source code. As I'm looking at it now (in the editor), there are three separate lines, all in typewriter font.  However, when I publish this, that is likely to change...

Topic by kelseymh    |  last reply


How to pre-record voice module from PC, avoiding using microphone?

Hello. Could anyone advice me, please? I read all of the QA related, but my question would be a bit specific. My intention is to make a greeting card like device, using recordable voice module. Recording your own message by using the microphone is pretty clear. However my concern is, I would like to pre-record this module with any music or jingle from the PC and leave user the option either to record her/his own message using the attached microphone or let that pre-recorded jingle play. I would use any of this type or similar modules shown on picture. Thanks in advance.

Question by Ardu Tube    |  last reply


Buy or Build a PC?

I'm having some trouble deciding whether to buy a bare bone kit computer for less and build it, or buy a more expensive pre-built one.Here's one of TigerDirect's bare bone kits-http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=3825393I like this one but the main problem is that I'm worried i will get all the connections messed up (serial cables, pin connectors, etc.) But it is about $100 less than this pre-built one belowhttp://www.bestbuy.com/site/olspage.jsp?skuId=8885575&type;=product&id;=1212192194316So here's the whole thing in short- the bare bone kit computer i might screw up, but it is a lot less than a pre-built one (I'll probably trust the pre-built one more).Please help me decide which one.

Topic by Caveman477    |  last reply



Building a bike light. 12v power source, 12v pre-built led fixture. Need SIMPLE way to make it flash.

I am building a cool bike light (which when finished, will be my first instructable).  I have a 12v power source and a pre-made 12v LED trailer tail light  that I am using for the light element.  What I need is something simple and cheap that I can build or buy to go in between the power and the lights to make it all flash.  Thanks in advance for whatever help that you can provide.

Question by chrisdoiron    |  last reply