Baracuda problem, beeps once

[Koala]

most likely this way



The wrong way round and the TIP127 will get hot in seconds unless you reduce the voltage to about 7-8 volts .

[barleg]

I got the barracuda working today, just reversed the 2222 like your picture Koala. Fiiiinally! Thank you for all your help here from the forum, it's been nice to have your backup and input. Now I'll start to build the frame =)

To summarize my problem with the barracuda for future barracuda builders:
The board beeped once and then got silent and the MOSFET quickly overheated. Turned out I'd got the wrong kind of MOSFET in the barracuda kit, an IRF510. I switched the MOSFET to a tip127 (irf9640 is also okay) and the barracuda started to work (continuous tone) but the problem with overheating remained. I changed the 2222 transitor on the board and reversed its pins. The MOSFET is no longer overheating.

[Koala]

That's good barieg. Well done. Really is a good detector for such a small component count.

Detectojer how is yours getting on ???

[6666]

http://cdn.instructables.com/FCE/GWL...VJIR.LARGE.jpg

[bluebenz1]

I have just built mine and had the same problem, 10v lion battery, beep once, so i reversed the 2222 and now get an adjustable continuous tone from the buzzer, I have an irf960 but this does get hot, is that ok or is there something else wrong I wonder?
PS....can anyone tell me how to to tune the trim pots properly...I can't seem to find anything on the net...!!!!!

[bluebenz1]

am now using a 9v battery the irc does not get hot now, any tips on how to tune the trim pots, am using a 26t .4mm coil, 200mm diameter. it is detecting a one pound coil around at 150mm, can this be improved?