TESORO GOLDEN SABRE

[der_fisherman]

But really nice smelling breath!!!

[Davor]

OK, the other alcoholic beverage of USA origin is aftershave. Gives you a splitting headache too

[der_fisherman]

Bourbon might also do the job, but what a waste!!!

[Davor]

...I forget what the name is in the USA, but its cleaning alcohol, its poisonous to drink...

bourbon

[der_fisherman]

You need to clean the flux off the PCB. I use Methylated spirits (I forget what the name is in the USA, but its cleaning alcohol, its poisonous to drink) and an old tooth brush.

Afterwards lay a piece of paper towel to get the dirty spirit away....it works quickly and effectively.

[Hornbuckle]

My device is powered by the power supply for the indoor antenna 12 V (100 mA), I also have a 12 volt battery pack. I turn on the power supply to the network and the metal detector starts beeping continuously when I raised the subject of the coil then he reacts to it.

http://www.youtube.com/watch?v=xX81eP_MDGE

video. MD

[Hornbuckle]

Have you a battery or a mains power supply? If mains supply, remove and try battery. You may have lots of mains noise in your house - try it on battery in a field. Is the buzz the same frequency as a valid target tone? S

My device is powered by the power supply for the indoor antenna 12 V (100 mA), I also have a 12 volt battery pack. I turn on the power supply to the network and the metal detector starts beeping continuously when I raised the subject of the coil then he reacts to it.

[golfnut]

Have you a battery or a mains power supply? If mains supply, remove and try battery. You may have lots of mains noise in your house - try it on battery in a field. Is the buzz the same frequency as a valid target tone? S

[Davor]

Your picture is not clear about what you did so far with your board. I tried to enlarge it and rotate in various ways, but I'm unable to read critical points. In case you connected capacitors in parallel, yes it can be a cause. Also if your op amps are not according to the schematic you can experience problems as you described. Problem is with some op amps that they behave completely unexpected if input voltages go beyond common mode voltages. LM358 is fine, and you can use it even as a comparator, but TL061 goes bezerk if any input goes down to negative rail.

As you'll want your rig to behave as it was designed to, it is advisable to replace those capacitors with proper values, and best choice are the non-polarised ones. You can't expect it to work properly with wrong time constants in filters. Once you fix that you'll see if the buzzing problem persists, and seek further if it does.

[Hornbuckle]

Yes, you can use ceramic, but these must be really big. A simple and cost effective way is using non-polarised capacitors at 4u7 or 10uF pairs in series connected back to back. The reason for back to back is that electrolytes leak in one direction.

Do you think if I put the two capacitor 10uf + - +, MD will no longer buzz after turning?
this is the number one problem, I do not know how to solve it...

[Davor]

Yes, you can use ceramic, but these must be really big. A simple and cost effective way is using non-polarised capacitors at 4u7 or 10uF pairs in series connected back to back. The reason for back to back is that electrolytes leak in one direction.

[Hornbuckle]

Comrade, you now have a 1.1uF capacitor! Connect two 10uF capacitors in series instead, and tie the middle by a high value resistor (megaohms) to some high or low potential, or the capacitors will wear out. Then again, if it works, why bother?

I have a ceramic capacitors, 4.7 microfarads. I can use them in the scheme?

[ODM]

Good morning, comrades, I made the wires shorter. 4.7 uF capacitor bi I have not found, made of two pieces of 2.2 uF

Comrade, you now have a 1.1uF capacitor! Connect two 10uF capacitors in series instead, and tie the middle by a high value resistor (megaohms) to some high or low potential, or the capacitors will wear out. Then again, if it works, why bother?

[Hornbuckle]

Good morning, comrades, I made the wires shorter. 4.7 uF capacitor bi I have not found, made of two pieces of 2.2 uF + - +, in all metal mode device works more or less normally. If I turn on the discrimination mode of headphones constant beeping sound, which I can `t remove the variable resistors and so on. the frequency of the coil TX 14.20 kHz. consumption of 60 mA device. 7808 - in 10.88v, out 7.95v (power supply 12V 100mA)

[Davor]

First thing to do is tidy your wires. There is no real need for coax anywhere, but you simply must avoid loops. Easy enough is to weave or twist the wires of same origin. Your coil connector jumper wires are ... well ... not tidy enough. And also a bit long. Be sure to twist them.