PicAxe Projects > PicAxe-08M 'Mad Cricket'

Finished PicAxe-08M Mad Cricket V3

 

Finished PicAxe-08M Mad Cricket V3

PicAxe08M Mad Cricket Schematic

PicAxe08M Mad Cricket Schematic -
Download the files here (UPDATED!)!

Circuit used: I drew up the circuit in Diptrace (you can download the free version for personal use) with information I got from Revolution Education Ltd.'s data sheets. You can download the prgramming software for free (Download it here!). Here is the program I wrote (download it here - UPDATED!). It is a text file; just rename to .bas. I used my PicAxe 08M Programmer/Proto Board to progam and test the circuit.

Construction Notes: Parts include: PicAxe 08m, 10M resistor, an 8 pin socket, cr2032 battery and socket, and a piezo speaker. Be sure to test your piezo. I found a wide variety of sound range and quality on similar piezos. I etched the PCB using the same method in my Making PCBs with Toner Transfer. You can download my Diptrace files here.

I was originally going to put in an on-off switch. But the only small switch I had was a momentary. Not good, so I opted for a jumper as an on-off switch. I couldn't get version 1 to work reliably. I didn't sort it out till after version 1.5. It was really a two part fix. First, I modified the program to put all pins low. Second, I added a 10M resistor between pins 3 and 7. I am not too sure exactly why I had to do this, but it works reliably now. I was trying to figure out why, when I touched the back of the 8 pin socket, it worked... Lots of probing and testing revealed the proper pins, but shorting them didn't work, only a high resistance connection worked. If anyone knows why, drop me a line. I didn't want to take the time to tin the board, so I didn't.

The program causes the piezo to emit a chirp like a cricket. Then wait approximately 20 seconds or so, then repeat. I went through about 20 or so combinations before my step-daughter started yelling at me to turn it off!

March 20, 2009: UPDATE: As I stated earlier, not all piezos are created equal. I found considerable variance in the amount of sound they put out. After playing with the program for about a week, I think I have a good mix. The file download includes the program (get it here). This is version 3. I trimmed the board a bit as well, making it a bit slimmer. The finished V3 cricket is shown above. See additional pictures below for more.

May 23, 2011 - Thanks to Andy the mystery is solved. The SerIn (pin 2) should have been grounded. This may solve the mystery of the 10M resistor as well. Thanks again Andy!

Version 1 Ready to Etch
Version 1 Ready to Etch
Parts
Original Parts Selection
Tinned and Drilled
xxxVersion 1 Ready to Etch
Version 2 Bottom with Magnet attached
Version 2 Bottom with Magnet attached
Version 2 Top

Version 2 from Top
Version 3 rounded PCB and slimmer
Version 3 with different piezos
Version 3 Bottom

Version 3 Bottoms
V3 Bottom with bigger piezo
V3 Bottom with bigger piezo

 

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