Hi all!
Thanks for having a look at my instructable!  If you have by chance seen my original clap-clap on/clap clap off circuit instructable.  This clapper circuit is very different than my original, in that it requires absolutely no amplification of the audio signal being sampled by the on-board electret microphone! As well, the circuitry is powered exclusively by the USB port on my PC!

For all of you who find this instructable interesting, I would apprecaite your vote in the USB contest.  As well, please rate this instructable.  If you found it to be good, I want to know!  If you found it needed work, I want to know!  Thank you for your consideration!
I'll be creating a kit for this instructable within the next few weeks, but without the relay. It will be available here:
Or here:

Here are some of the key features:
* By simply turning your computer on, you can clap-clap on anything powered by AC that is within the limit of the 5v relay you are using (A desk lamp for example - Seen in the below video)


* No amplifier circuitry required.  The audio is sampled through the use of an ADC (Analog to Digital Converter), located on the MCU.

* Powered SAFELY by the USB port on your PC or laptop.


Step 1: How It Works!

There are many different variations of the clap circuit.  You can have circuits that activate when it hears a loud noise (clap), and deactivates when it hears another.  Typical clap circuits, such as the one I created in my second instructable requires two loud noises (claps) within a very short period of time to activate the circuit, then anoother two claps do deactivate the circuit.  This is all done through simple programming. 

The electronic hardware is very limited, which is great, as most of us don't have a ton of money to spend on our side projects.  I'm very proud of this fact.  I've never seen any version of the clapper that used an ADC to sample for noise.  All of my previous clap circuits, and all of the other clap circuit variations that I've seen require either passive or active amplification.  It took a bit of time to get the programming right.... I had to make many changes to several timing registers before I was content with the result.

The CIRCUIT SCHEMATIC on the following page includes an in depth analysis of the simple circuitry involved.  You should have no problem following along.  For now, let's talk about the basic theory behind the circuit.  As well, if you've watched the video, you'll have seen a schematic breakdown from myself personally.

1)  As soon as the devive is plugged into the USB port of the computer, it becomes active.  By active, I mean that is is constantly scanning for loud noises, such as a clap.

2)  As soon as the device detects a loud enough noise, it starts a countdown sequence.  In this very short time, the device is constantly scanning for a second loud noise.  The duration of the countdown sequence is under 600 milliseconds. 

3) If within the period of the countdown sequence a second loud noise is detected, the microprocessor activates a relay, which is connected to an AC power source, and a load that requires AC (A lamp, fan, LCD,etc).  If the countdown sequence elapses without another noise being detected, then the program starts over, and scans for an initial loud noise.  This is to ensure that two claps are required for activation, not just one.

4)  If the device detected two claps, your relay is now activated, and your AC device is powered.  The program now goes into an extremely similar area of the program that basically mimics the first part of the program.  It waits for another set of claps, only this time the relay will deactivate if two claps are detected. 

5)  If two more claps are detected within the countdown sequence, the relay is deactivated, and the AC device turns off.  The program then starts over.

It is a very simple programming algorithm.  I decided to use the PIC10F222 Microprocessor (MCU), which is EXTREMELY cheap - Less than $1 if purchased in bulk).  The problem with the PIC10 series, is that it is an archiac MCU, and it comes without the BTG (Bit toggle)  and COMPARE commands.  This made programming the MCU a pretty large pain in the butt.  It requires a lot more code, and a TON more patience.  I've provided the code in the SOFTWARE step, so have a look at it.  I've done my best to comment the code, so try to follow along with it!

That's right!  No amplifier!  The coupled signal coming from the microphone is so small that it typically requires amplification in order to be compatible with the PIC.  What I've done here is, through programming, taken readings from the ADC, and looked for signals in the 20-40 millivolt range (0.02-0.04 volts).  If the noise is loud enough, the ADC is able to pick up that small signal, and turn it into a hexadecimal value, which is then compared against a pre-loaded value.  If the signal is stronger than 20mv, then it is accepted by the programming as a "CLAP".

The PIC10F222 has an internal ADC capability that allows for the user to sample an analog signal between 0v and 5v.  This analog value is then turned into a HEX value based on a binary number.  This is an 8-bit HEX value. 
If we have 5v at our analog input, and we take a sample, the value in the ADC register will be "1111 1111, which equals FF in HEX"
If we have 0v at our analog input, and we take a sample, the value in the ADC register will be "0000 0000, which equals 00 in HEX"
In the programming, I run a routine that samples the voltage at the ADC input, and if the value is 0000 0001 (01H) or greater, it is recognized by the program as a "Clap".
COMPONENT LIST (Using USB as the power supply):
* Electret/Condenser microphone
* PIC10F222 MCU 8-pin DIP IC
* USB cable
* Terminal Block
* 5v relay
* NPN small signal transistor, such as 2N2222, 2N4401, or S9013
* Dollar Store power bar
* Resistors: 470R / 100k / 2x 10k
* Red LED
* N4004 diode
* Capacitors: 2x 0.1uf / 10uf
* Prototyping PCB (5cm / 7cm)

1) Soldering Iron
2) Glue Gun
3) Safety Goggles
4) Patience
5) Some soldering experience

hello do you think that it's possible to use pic12f675 instead? <br>
<p>also wanna know if i can use the same code but change the pins</p>
I managed to write your code in C so the code can work with most MCUs, can u tell me how long are the delays in your asm code?<br><br>Cherz
<p>do you still have the c code?</p>
is your c code working??
<p>Hey Pat About the code do you still have the .hex file format or is it possible to put it in 16F628A PIC? or There are changes in the code so that it can compile to 16F628A?</p>
hey a very good and simple tutorial and great explanation :) i just nw saw your kit in the ebay store but i already purchased the components except pic10f222 MCU and i would like to ask you how to program that MCU? is it easy to program??? and thanks in advance. and i just wanted to ask you if u can ship only the programmed MCU to INDIA??? thanks again. :)
Hi. I have a problem when transferring the hexfile into my pic10f220 :/ <br>It's says that the OSCCAL value in invalid, and i can't &quot;Auto regenerate&quot; it. <br>So I wondering if you know the OSCCAL value so I can set I manually? <br>(Error: 0x000000) <br>Thanks! :) <br>
It is possible to do it with pic12f683 : http://embedded-lab.com/blog/?p=6439 <br> <br>thank you! <br>marC:)
Dude this is amazing!<br>I understood the most of the steps except for the code, could u plz upload a flowchart of the code if possible?
Can u please E-mail me the diagram of this clap switch that works without connecting to the usb port<br>My email id is sanjvwin10@gmail.com
can i connect the ac power directly without using a power bar?<br>
This is exactly what I was looking for! However, I am a bit confused, do the claps only turn on one specific object? Or can they turn on any object connected to the power strip?<br><br>I'll wait until the kit comes out to make things easier, thank again for the instructable!
Kit is on the way! Custom PCB and all =) By Christmas. The PCBs have been manufactured, and are on the way to my home. Check out engineerigshock.com for all of our new kits =)
Hi there <br>Yes, anything on the power bar can be turned on. You have to keep in mind the power rating of the Relay, as the leads can only handle so much power. These relays can handle a ton of current, but I wouldn't use it to power your microwave =) Thanks for the comment! <br>Pat
We want the kit!
Kit is on the way! Custom PCB and all =) By Christmas. The PCBs have been manufactured, and are on the way to my home. Check out engineerigshock.com for all of our new kits =)
Nice!<br><br>I had to adapt the detection level to 5D = 0000 0101B because the relay was going to ON and OFF in a loop. I guess this is due to the very low level of detection and to wireless like Wifi or alike.<br><br>Thanks for this nice project, I'll maybe amplify the mic with a single transistor.
Thanks! <br>I'm wondering why you had to change anything. You shouldn't need to amplify the mic signal, as the ADC should pick up the smallest sounds. However, changing the value in the detection register can easily change your sensitivity. Did you use the same components? <br> <br>So glad someone re-created this. Do you have a video? <br> <br>Thanks again <br>Pat
I have a small knowledge of basic electronics and it ends on repairing TVs and radios only. This is a nice tutorial. Thank you for sharing it..<br><br><a href="http://iamdavie.com/sams-club-credit-card/">sams club credit card</a>
This is great. I have tried the clap clap on/ off circuit you did and works nice. But this is even better because you don't need any amplifier. I think I could do it with a PIC 12f629. Nice job!.<br>PS: Is it possible to use a triac instead of a relay switch?
Hi there <br>Thank you for the comment =) As long as the Triac will turn on completely using a 5v signal, and is properly heat sinked, then I think it'd be a great idea =) <br>Let me know how it turns out! If you have time, please rate my instructable. <br>Thanks again for the comment. If you end up making a video, please send it my way! <br> <br>Thanks <br>Pat
Great job! I have been working on one of theese but I was worried about the amplifier circuit...BUT NOT NOW!!!
Hi there <br>Thanks for the comment =) If you still want to incorporate an amplifier, check my channel out. I hvae a another clap clap circuit that incorporates a simple active amplifier (LM324). Thanks again take taking an interest. Please rate my instructable if you have the time =) <br> <br>Sincerely, <br>Pat
This is the first time I have visited your site and I am amazed at the amount, the value and the clarity of the information you have provided. This was beautiful and very thought-provoking. <br><a href="http://go4download.com/hp-laserjet-p1102w-derivers">HP LaserJet P1102w</a>
Thank you very much =)
I absolutely love this project and would like to try it out myself. However, just one question, is there a less expensive programming kit that we could use to program the pic10f222? I'm asking because from what I've searched the kits are extremely expensive, specially for something that i'll use maybe once or twice =/ thanks in advance! Great instructable btw =)
Hi there <br>Thanks for the comment =) In the coming week, I'll be placing a kit in my ebay store for this. It will include the programmed PIC, the microphone, and all of the other passive components, minus the relay and relay driver. If you are still interested in a week, and you don't see the kit in my store, let me know =) <br> <br>Thanks! <br>Pat
You know those dirt cheap tiny USB wall chargers? You should build that directly into the AC line (before the relay so it's always on) to power your 5V circuitry.
Good call. <br>However, I wanted to have this interfaced with my PC. As well, the dollar store power bars are hard to modify internally. The bars are connected in parallel through metal bars, not wires, which means you have to but the bars internally. I've tried, and it can get messy. Good call though. I see what you're getting at =)

About This Instructable


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Bio: Hi there! My name is Patrick, and I am an electronics engineering technician who works full time as a lab tech, and part time as ... More »
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