about proscan pi metal detector

[New THer]

I tried the corrections that i found in this page but its still not working.I think that the bd 911 is overheating (i can't touch it),is this normal?thanx guys

[Russ]

Re: about proscan pi metal detector

I haven't tried out the proscan circuit but the transmit circuits of most PI detectors are very similar. Most of the PI detector designs I have seen use the IRF740 Power Mosfet as the TX switch. It is a 400 volt device. I have tried the IRF520 which is a 100 volt device and it works but does get quite hot without a heat sink, though it hasn't died yet, at least in my testing. One additional circuit I have seen uses a 2N3055. I have no idea what the specs are for the BD911. Due to the current thru these transistors I seriously doubt that any of them will not get warm to hot, especially at higher TX frequencies (higher duty cycle). In order to really troubleshoot the circuit you will need a good oscilloscope to check that all the pulse timing and pulse widths are what they should be, and that the amplifiers are working properly. Sorry I can't be of more help.
Good Luck
Russ

[Russ]

Re: about proscan (other ideas)

Sorry, After posting my first response I read your earlier question and I see that you are somewhat inexperienced in electronics. Thats ok,, I sure wouldn't want to discourage anyone from trying to build their own detector. But without the test equipment and a fair understanding of electronics it makes it more difficult, and makes it extremely important that all of the instructions stated by the designer be followed precisely. That is don't substitute any parts ( voltage and wattage ratings are important). Be very critical in checking and rechecking all solder connections. Make sure that all polarized components are inserted properly ( electrolytic capacitors, diodes, transistors, and IC's). If at all possible borrow or buy a Volt/Ohm Meter and measure the DC voltage levels at the outputs of the regulators and at the inputs to all the IC's. If all this fails, seek out and make friends with someone in your area who has the experience and test equipment and who would be willing to help you with troubleshooting the circuit. If you happen to be in Upstate NY, send me an e-mail.
I hope this helps,, and Good Luck
Russ

[Esteban Cabrera Grinok]

Re: about proscan (other ideas)

Hi,

My friend Carlos, from Argentine, is the "master" respect the Proscan. He built this detector and he assure me is very good. He love this circuit. He replace the 709 for the LM318, the BD911 for IRF740, etc.

[Carlos]

Re: about proscan (other ideas)

I was thinking about the misfortune to arm a circuit and that does not work. I see that many people do not have suitable instruments to detect where this the fault and I put myself to think that a possible alternative is to develop to a measurer of period with any quartz Xtal and any register like being CD4017 or a CD 4514 with LED to interpret the times of circuits PI. If somebody has some idea to improve my commentaries, with taste incorporate to the forum.


Carlos

[New THer]

Re: about proscan pi metal detector

First of all i want to thank you all guys.
I thought to use winscope as osciloscope.Is this program good for what i want to do?Where i must connect it and what measurements i must get when the detector works fine?
Thanx another time guys

[New THer]

Re: about proscan (other ideas)

Hi carlos.I want to ask you about the changes you did to the proscan pi?I wonder if you can tell me (one by one) so i can see mine to works to.Thank you very much.

[Viktor Romanov]

re...BD 911

Hello !

No any warm from 911. See bd 911.pdf and correct circuit.