IDX-PRO+VDI

[szucs_g]

These PCB's. The transistor is vice versa. The legs good order. I'm sorry!

Voilá the modified PCB:

[szucs_g]

These PCB's. The transistor is vice versa. The legs good order. I'm sorry!

[szucs_g]

hi szucs_g,
I have the same problem. my MPSA13 is also hot, and then goes off. :-(
Unfortunately I am still not found out why this is. I just wait for a new delivery MPSA13.
in the treat is only written, the VR3 is there to adjust the phase.



Happy Easter, marc

Thank You!

The PCB is faulty. The original transistor BCE, but the MPSA EBC. Also changed a bit, beenelem the image here. I know this is not the original PCB, but unfortunately I could in this residue. The dealer got me BC879. This is absolutely not good. I need MPSA13, 14 or BC517!

Christ is risen!

[Schatztaucher]

@ gurdal:

looks nice!

[Schatztaucher]

hi juice, I wanted to hear this ... I've also thought that it could be the speakers. had the speakers on shelf yet. But before I even picked out a piezo speaker. when there are new MPSA13, I'll try it again.

[gurdal]

Are you using the peizo that came with the pcb. I burnt one Mpsa13 up because I hooked a 4ohm speaker up to the pcb. I noticed my mistake, changed the transistor then changed to a 8ohm speaker and it is working now. Although I am still trying to get the coil right.

Hello, my IDX PRO VDI

http://img189.imageshack.us/img189/2314/sdc10019i.jpg

[juice2839]

mpsa13

Are you using the peizo that came with the pcb. I burnt one Mpsa13 up because I hooked a 4ohm speaker up to the pcb. I noticed my mistake, changed the transistor then changed to a 8ohm speaker and it is working now. Although I am still trying to get the coil right.

[Schatztaucher]

hi szucs_g,
I have the same problem. my MPSA13 is also hot, and then goes off. :-(
Unfortunately I am still not found out why this is. I just wait for a new delivery MPSA13.
in the treat is only written, the VR3 is there to adjust the phase.



Happy Easter, marc

[szucs_g]

Sorry for the stupid question of! What is the role of the VR3's?

[szucs_g]

Stuck. Soldered all the parts. Each IC is in place. The head is in place. Power on. High frequency noise coming from the speaker. The Darlington transistor is heating up. The electronics are not detected.

I think it should stay szakmámnál (anesthesiologists). :-)
Unfortunately, the meter did not bring with me, so I can not weigh out what is wrong. :-(

And... BC879 substituted in the circuit MPSA13.

[szucs_g]

Stuck! Heeeelp!

Stuck. Soldered all the parts. Each IC is in place. The head is in place. Power on. High frequency noise coming from the speaker. The Darlington transistor is heating up. The electronics are not detected.

I think it should stay szakmámnál (anesthesiologists). :-)
Unfortunately, the meter did not bring with me, so I can not weigh out what is wrong. :-(

[juice2839]

Thanks for the suggestion. I changed out the lm324 with a op940 and same thing. I used a .0033 uf cap on the RX coil? is it supposed to be .0033uf or .033uf? I have rx resistance of 43ohms and tx resistance of 1.9 ohms. Do I need a 51ohm resistor in series with the RX coil? Thanks abounch for the help.

[dfbowers]

Check the offset of the last stages of your LM324. I will bet that it's 5 - 10MV negative. Replacing the LM324 with an LF347 will most likely fix it if that's the case. With a home built 10" coil I can squeeze 19"out of mine for a U.S. Quarter. Problem is, only about the first 12" is usable as it becomes unstable at high sensitivity setting, even with a stock coil.

Stock coil -> http://www.youtube.com/watch?v=BmwMIynbJSk

Homebuilt coils - > http://www.youtube.com/watch?v=qDyZXoC2lJk

http://www.youtube.com/watch?v=lIbAG_UFMmM&feature=relmfu

Don

[juice2839]

IDX Depth

I have finished building Silverdogs IDX pro kit. I have also wound a homemade coil per the specs I found in this thread. I am getting about 6 inches on a US Quarter and about 5 inches on US penny, nickel, dime. Does this sound about right for a homemade coil? Or is it really lacking in depth? These depths were in air with no discrimination. If I put it in PP mode I can detect deeper by listening to the tone increase/change. Also the Disc seems to come on very quick with the pot. IE 1/4 turn and I loose nickels foil and alot of depth on pennies and quarters (maybe detects them at 2-3 inches). Thanks for any replies.

[mikebg]

Mikebg Thanks for your comments. You are a machine! Best regards!

NOT!
I have time only for one or two posts per week.
I was a radio amateur, which hobby was to design TXs, RXs and antennas for QRP amateur radio.
QRP means "Decrease TX power". Now I try to increase TX power in IDX and other metal detectors, which is absolurely stupid according the QRP principle.
However most participants in this forum think that more TX power means more depth of detecting. Let they experiment the more poweful TX circuits to see what happens with AIR&GND signal