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:
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)
* EXTREMELY LITTLE HARDWARE REQUIRED! Less than $10
* 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.
THIS VIDEO TALKS ABOUT THE PROJECT, GIVES YOU A DEMONSTRATION, AND TALKS ABOUT THE SCHEMATIC DIAGRAM!
Step 1: How It Works!
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
5) Some soldering experience