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Yep,
Please below is dents waves from LM13600 and it change with tone control,
Please below is dents waves from LM13600 and it change with tone control,
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Problem seems to be from circuits related to the coil, see the coil signal picture.Comment
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Yes you are correct, the coil pulsing is not working correctly.
After the tx pulse turns off, the flyback voltage should be going up to +180v.
What coil do you have? Resistance and inductance and self resonant frequency.
Also, if yo could measure the current waveform going into the coil that would be helpful.
Cheers MickComment
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Yes, the scope pic of the coil pulsing looks goofy.Comment
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That audio VCO section would not be a problem. If the waveform is changing with the tone control then that's to be expected.Originally posted by Anis View Post
LM13600 is old chip from eighties I think.Comment
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Originally posted by Mechanic View PostOriginally posted by dbanner View Post
Not sure if the 'coil pulsing" scope pic is correct or not.
Seems that the IRF710 on the TRANSMIT page of schematic may be a flyback clamp.
Anis, you have a two channel scope.
I would like to see the Coil and the logic pulse in one scope picture. This way we can directly compare the timing.
I agree with everyone that this is a complex circuit and not easy to understand.Comment
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Mick is correct! Also, remember, there is a circuit that controls the max voltage of the flyback (and the Vds biasing of the TX MOSFETs during the off condition). If that circuit (in particular the biasing of the TLC271... I would suspect the LM336 layout as there is an error in the original schematic) is not correct, the IRF710 MOSFET in the circuit could be draining/shunting off the flyback voltage.Originally posted by Mechanic View PostComment
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Originally posted by KingJL View Post
Also, if the correct voltage is never met on the +180v cap, then the front end fets stay in an off state.
Cheers MickComment
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I would be really suspicious of the 2.5V (supplied by the LM336) for three reasons: (1) The original schematic is ambiguous to the correct connection and the 2.5V should really be labeled -2.5 V (although studying the circuit and understanding it will allow you to sort it out), (2) if the 2.5 V is incorrect you will have problems with the +5V generation, (3) if the 2.5 V is incorrect, the flyback regulation circuit will be incorrectly biased and will not function properly (and like Mick says the front end is blocked). All of which seems to apply here!Originally posted by Mechanic View PostComment
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Front end can be blocked because of those 180v or mistakes around the input mosfet transistors or defective transistors or 4093 does not open them signal from the transmitter not good on an oscilloscope..Originally posted by KingJL View PostComment
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It's an honor to comuonicate with all of you nice peapole; I m very thanful for all the support that i m recieving;
till the moment i v been cheking the layout for mistakes and now i m collecting informations as per all requestes, so once i complete I will upload then i m sure we will get the reason for.
thanks a lot againComment
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back again,
Mick,
Please below is answer to your questions:
1-What coil do you have?
Home made coil using H07VU wire (1.5m2 section)
R=0.5 ohm
f=24.62 KHz
L=204uH (calculated ; parallel C=0.205 uF capacitor)
2-Also, if yo could measure the current waveform going into the coil that would be helpful. see attached both waves for coil voltage and curent.
Waltr,
Please see attached is both voltage waves from coil and from CCT with coil connected and no for the other.
KingJL,
Please below is the scope for 62KHz test point and 2.5 ref.
Hope that I vn't miss anythink,
waiting your comments, till that wish you good night
Cheers J.AComment
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Foolish question... what are the actual parts you are using in the TX circuit... e.g. TX MOSFETs, diodes, etc? If you are actually using BUK455, which one... there are at least 4 different ones -60a, -100a, 200a, and -600b? And for the diode, is it the BYV28-200? If you temporarily remove the diode between the TX drain and 100uF capacitor, do your TX current/voltage waveforms change... particularly the end of TX/flyback time? Currently the flyback is extending for about 120 usec... indicating an almost complete shunt of the flyback. The polarity of the 100uF/200V capacitor?Originally posted by Anis View PostComment
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Your coil should be around 0.4r and 300uh self resonant frequency between 250 and 750khz.
The wire needs to be multi-stranded. Minelab uses litz, but a tin coated multistrand wire seems to work ok.
Your current waveform doesn't look right. The current should rise to about 2.5A over the tx period and then just fall back to 0 after tx off.
Your picture with no coil, the tx pulse looks like it has a fairly slow risetime? Where is the other pulse(ch2) taken from?
Do you have the tab of the irf710 connected to gnd? Make sure the tab is isolated.
Cheers MickComment
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Working correctly, the irf710 drain on mine shows a constant 180 volts. Might want to check yours.
Also, from experience, after loosing a power supply fet due to a short, I also lost a front end receive fet (VN2410L) possibly because it no longer had the power to switch.
Mine now shows a full 10 volts across 5+/5- rails.
And, I attempted to make a coil using litz wire but if I got the inductance at 300uh, I couldn't get the resistance right. I ended up buying a mlab coil.
There is a wealth of info in this thread starting around page 18.Comment
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