Voodoo Main Discussion

[godigit1]

Were you able to zero this out?

Hi Lamoiz,
Thanks for posting the specs on your coil.
Are you balancing on detector?

[MartyJ1963]

Thanks George. I can start sorting my Detector shaft and enclosure now so I can estimate the cable I'll need for the LCD then I can solder the LCD wires in and move to the next stage. Regards, Marty

[Qiaozhi]

Hi All,,,I changed the diodes D6 and D7 but still didn't get 12v at the cathode of D6. I have +5v and -5v though so I'm lost what to do next? Thanks, Marty.

Since you have +5V and -5V you're OK to continue. The voltage at D6 is not going to reach exactly 12V. It only needs to be higher than 5V plus the dropout voltage of the regulator.

[MartyJ1963]

Hi All,,,I changed the diodes D6 and D7 but still didn't get 12v at the cathode of D6. I have +5v and -5v though so I'm lost what to do next? Thanks, Marty.

[MartyJ1963]

Thanks 6666,,,Learning something new every day! I've never had a problem like that with any of the power supplies of any other detector I've built so this is probably why I never knew what to look for,,Lol. I've changed the 78L05 now. Out of a new bag of 10 x 78L05's, the first 3 that I tried replacing were faulty too!,,Anyway, I now have my +5v and my -5v on TP14 and TP15,,,but, I only have 7.4-7.5v on the cathode of D6. Shall I change that diode too? Thanks again for the help and I hope your wife is recovering ok, Regards, Marty.

[6666]

Thanks George. I'll replace the 78L05 to see if it rectfies the problem. I don't understand what you mean about something 'loading' its output pin? Thanks, Marty.

Sometimes a fault will put such a high current drain (load) on the circuit the battery voltage drops

[MartinB]

yes, I think it is, because it is an old spool of thread that I have had in my workshop for a very long time, and there is no longer the informative label. silicone and silver color.

Let me know how the coil performs. I have heard that the silver plating creates eddy currents and reduces coil performance

[MartyJ1963]

Thanks George. I'll replace the 78L05 to see if it rectfies the problem. I don't understand what you mean about something 'loading' its output pin? Thanks, Marty.

[Qiaozhi]

Hi George,,I removed the 78L05 and the voltage at the cathode of D6 is 9.89v. Thanks, Marty.

In that case either the 78L05 is faulty or there's something loading its output pin.

[MartyJ1963]

Hi George,,I removed the 78L05 and the voltage at the cathode of D6 is 9.89v. Thanks, Marty.

[lamoiz]

oops I said stupidity, it is a 20k .. sorry ..

[Qiaozhi]

Hi Alec,,,No, I only have 8.42v at the cathode of D6. And still only 0.76v on TP15. Thanks, Marty.

Remove the 78L05 and measure the voltage at D6 cathode again.

[lamoiz]

Hi Lamoiz,,,I posted pictures of the power supply on page 15 post #352. Regards, Marty.

are you on the value of r48? 10k?
brown black black red brown.

[MartyJ1963]

Hi Lamoiz,,,I posted pictures of the power supply on page 15 post #352. Regards, Marty.

[lamoiz]

take a picture of your circuit ...