The TP1 Waveform

[1843]

Carl,
I think that my battery is bad;
With each beep it has a voltage drop about 3mV.(Without coil installing)
It is very high for a 8Ah battery.
I want to buy one new battery... What kind of them is better?

I have made the through-hole PCB.

Best regards

[Carl-NC]

3mV out of 12V is only 0.025%, this should not be a problem.

[Bill]

I forgot this but I ran into the same problem. I added an external amp and shielding, tantalums, etc but still never got rid of that damn beep. I always attributed it to my wifi or some other noise source. I forgot all about this when I bought my GB2 and I think I should probibally have a go at fixing it before I take the HH on my trip. Ill give it a shot this weekend.

Will

[1843]

I couldn't repair it..
Now I am building another HH!

[Bill]

I plan on doing the same as well but I want to see if I can fix the old one. I plan on building a similar PI to the HH but I want to use a different front end along with a different power supply set up and some newer faster op amps.

[1843]

+5V

Hi,
IC2 output swings about +-10mV.
Can it cause the problem???

Thanks in advance.

[1843]

My new Hammerhead works so good!!!

Many thanks to Carl, bbsailor & Reg.
My second HH works so good and it can detect a sigle coin (2 cm diameter) at 17 cm with 3.5 inch coil! Also it can detect a soda can (330 ml) at 50 cm!!!
I enjoy when I am working with it!
Again thanks to Carl for his design.

Best Regards,
1843

[1843]

I still cannot explain the funky TP1...

Hi Carl,

I found the reason of that! It was due to 555! Its part number is NE555N. I think it is a TTL version.

I added an 1k resistor to pin3 of it for pulling up. The funky waveform became clear. But its rise time still is not good... it is about 5us which doesn't allow to MOSFET turns off quickly.

What is your idea?

Thanks in advance