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ahh now i know what you mean sorry i thought i was missing something, yep no delay between the signals. I have looked at post 210 and all the components are in the correct place. i have a spare 10k pot i can put across the external delay pot connections?
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That looks OK but over damped. It is 20-30% better than what you had with the longer cable. This means the damping resistor is too small of a value. We will deal with that later.Originally posted by Impulse View Post
Please remind me later.Comment
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The problem is with the delay generator U4f, c5 and r10. Something is wrong there. I think the signals pin 2,4 of 40106 have no delay between them because the signal getting to them is too small, it is just a spurious signal that is actually coming from crosstalk between the transmit pulse generator U4 d and e and the imput to the delay u4 f. I thin if we fix the underline part above the circuit will work.Originally posted by Impulse View Post
The 10K pot you have will work great, just set it for max resistance between the center pin and the left pin as viewed with the pins facing down. If you get this correct clockwise rotation of the pot should increase the resistance and the delay. This is the OPPOSITE of the trimmer where clockwise rotation decrease the delay which is illogical and confusing. Then cut the delay pot Link on the board with a sharp knife a measure between the two PCB pads to ensure you have cut it. Lastly solder the two wire from the 10 k external pot. And take traces at pins 2 and 4.
Make sure you are clear what trace ( Link) to cut before doing it. Ask if this is not clear.Comment
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KT I think the problem is those strobes are not being fed the right signal from U4 f, the signals are too small to properly toggle the Schmidt inverters so what you seeing is just a pulse on the rising and falling edge of the transmit signal due to crosstalk. Since this is synchronous with the transmitter there is no delay between the signals. The 40106 has a hysteresis of .9 volt with a 5 volt supply so it will not respond to voltage below that. In this circuit there is a lot of crosstalk, that part if the design looks less than optimum.Originally posted by kt315 View PostComment
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KT 315 So there is about a 200 uS delay between the 2 strobes? You did not state the time per div and volt per div.
Thanks for you help!Comment
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ok i have CUT the link and put the 10k pot in its place
hereComment
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http://storage4.static.itmages.ru/i/...19e4cc22d4.jpgOriginally posted by Old cart View Post
take attention 'zero/ground/GND' is a top of the signals just cause 40106 supplies from GND and -E (look at my first pic).
14 pin, plus pin, stay on GND; 7 pin stay on -E.Comment
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This is progress! Try depth test now. Have you got a .1uf cap? If so please solder it, with the leads cut as short as possible. One the back of the board between pins 7 and 14 on the 40106. Remember the pins are upside down and reversed becuase this is the back of the board so confirm before soldering.Originally posted by Impulse View PostComment
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KT is this from the PCB you designed? If so it looks much better than the Sliverdog board!Originally posted by kt315 View PostComment
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Your schematic is the same as Silverdog??? So you must have better board layout!Originally posted by kt315 View Postyup... from my pcb... thank you...
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ok i have just tried an air test with a gold ring and i get a positive 6" BEEP then after that it is faint but i still cannot move it around, i have the delay trim set at 10k ohms and the delay trim pot at full (10k ohm)
old cart i do not have a 1uf cap that i can solder to pins 7 and 14Comment
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my layout is a copy of original board. i did not learn silverdog pcb, 'papa alex' pics and his photos of the board gave me
enough info.Comment
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can i buy one of yours it works betterOriginally posted by kt315 View Postyup... from my pcb... thank you...
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