xr-71 sniffer powerscan coil

[kt315]

Delta pulse will work with all the coils you point to, but with none of them you will not get maximum results. The meaning of setting this damping resistor is when you work with just one particular coil. With another coil the value of the resistor will be different.

on old schematics of DP and XR71 both damping resistor has value 2k2. it was enough then why it is not enough now?
i changed the value to 680 and that sure enough.
pls do not write nonsence.

[dbanner]

This is true, except we do not know the frequency nor sampling of this particular kit since he has not posted schematic. Aside from ringing, the inductance of coil becomes important to its sensitivity.

[dbanner]

Is the thing working at all? Post the schematic that came with kit.

[Sulyman27]

See the Schematic and instructions.

[homefire]

I have one of these put away waiting to put together for someone when I complete another project for him. Let me know if I can do anything for you guys.

[dbanner]

Looks like nice kit, so what's the problem? Did the PCB come pre-assembled? Just use the coil you built for testing that it works, then you can move on to tweaking with it. The 2K resistor for damping will be fine.

[Sulyman27]

Yes, the pcb comes pre-assembled,
Iwill install the potentiometers an switches..and test it with my coil tomorrow..
Thank you all.

[dbanner]

Drill some holes into something and mount the pots and label them, so you know which is which, be very careful when connecting coil not to short coil wires. Also make sure battery correct polarity etc. Good luck.

[Sulyman27]

Hello, guys
I have a problem with my xr-71 sniffer pcb, The fuses on the board and on the panel blow when i turn the detector on, First time operating there is a heat with mosfet IRF740 and then fuses blowing, what causing that ??.. Any help pls

[kt315]

check voltage on logic ICs. frequent reason is burnt diodes 1N4148 in power line.
in last revision of my board i set 1N4004 to fix that problem.

PS. desolder mosfet on the check time

[eclipse]

Dont connect the coil next time when you test. You should connect the coil only when you know the mosfet switches and thats why you need to measure the signal on the Gate of the mosfet. If theres no signal my guess would be like what kt315 says. I hope you havent spent alot on that board.

[dbanner]

You are in for one hell of a ****storm with your project. Get out now while you still can.

[dbanner]

You will need to do some basic troubleshooting on pcb. If you are good at electronics, then you can fix this board very easy, if you are incompetent at electronics, then you are like blind man stumbling around in dark room.

[eclipse]

I don't think it's his fault his got c.r.a.p.p.y board. Board should have protection so that the transistor doesn't blow but the fuse, also the trouble with the power supply in this circuit has been found, discussed and fixed a long time ago so stuff like that doesn't happen. Some sellers just never learn.

[kt315]

my board size vs size of the board of Gueorgui 'mustang'