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No MPSA13, how substitution?
No MPSA14, how substitution?
I only BC548 how Darlington?
No MPSA14, how substitution?
I only BC548 how Darlington?
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if you can not find Darlington around... use two N-P-N type transistors according the structure you see above. there is not problem to get a Darlington...connect them both what you see on the picture.Originally posted by yhl View Post
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Surfmaster not working
I have built the circuit using Oxygen's layout, and have watched out for the common pitfalls (like inserting that specific transistor reversed), so I have a degree of confidence that it should work. However, it does not. I checked it with a scope, but could not find any obvious errors (although I am far from understanding how it should work).
On the following shots, channel 2 is always showing the 5534's output (pin 6), while channel 1 is showing various spots.
4066, pin 2 (signal after the sampler switch)
LM358, pin 5, 6, 7:
LM358, pin 2 (threshold input):
4066, pin 5 (2nd sample control signal) and pin 13 (1st sample control signal):
When I close on a piece of metal, nothing visible happens after the 1st OPA (integrator, after the sampler). I find suspicious that its output is so small... I would have expected a larger signal there.
Does anyone have any advice where I should be looking?
Many thanks.Comment
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yes and at somepoint i will do business with him, prpberly the chance pi when there available on the other hand i do like to make my own pcbs etc and this particular project I have quite alots of the components in stock and it appears quite stright forward after watching everyone else iron out the bugs.Originally posted by Qiaozhi View Post
God i sound so selfish, but im not really
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So if anyone here would be so kind to upload the PCB,layout, and a very recent circuit diagram i would be greatful.
I have never made a PI detector before so this is my first.
Many thanks in advance
DaveComment
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I got quite a few of the MPSA14 in stock they were cheap, if you want one or two drop me a line with your address and i will post them to you.Originally posted by yhl View Post
RegardsComment
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say exact what you want maybe i can help thanOriginally posted by satdaveuk View Post
surf pi singlesided pcb ( search for oxygen layout)
or double sided pcb?
or another projectComment
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Single sided surf is what im after BernteOriginally posted by bernte_one View Post
thank youComment
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I have this single sided version from James Owen, I was going to get some boards made but other projects took over !Originally posted by satdaveuk View Post
Q6 silkcreen is wrong, rotate the mpsa13 when inserting
Silverdog
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thx silverdogComment
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Thanks
Thanks Silverdog your a diamond, also thanks for your time Bernte
RegardsComment
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SFThomas:
I have not built the Oxygen board, there were some comments earlier in this thread that it contained errors, although i have not checked it myself, but your waveforms look good. Transmitter and gating pulses look OK. You should be able to see the change in the decay curve on the output of the NE5534 when placing a large target near the coil.
Reagrds, James.Comment
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Have a look on page 2 of this thread, ApBerg shows some scope pics for delay settings, if you sampling at the wrong time you won't detect anythingOriginally posted by sfthomas View PostI have built the circuit using Oxygen's layout, and have watched out for the common pitfalls (like inserting that specific transistor reversed), so I have a degree of confidence that it should work. However, it does not. I checked it with a scope, but could not find any obvious errors (although I am far from understanding how it should work).
On the following shots, channel 2 is always showing the 5534's output (pin 6), while channel 1 is showing various spots.
4066, pin 2 (signal after the sampler switch)
LM358, pin 5, 6, 7:
LM358, pin 2 (threshold input):
4066, pin 5 (2nd sample control signal) and pin 13 (1st sample control signal):
When I close on a piece of metal, nothing visible happens after the 1st OPA (integrator, after the sampler). I find suspicious that its output is so small... I would have expected a larger signal there.
Does anyone have any advice where I should be looking?
Many thanks.
http://www.geotech1.com/forums/showthread.php?t=17240Comment
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The sample timings look OK, the first sample window can be seen to cover the delay curve in the bottom right scope capture.
If anyone decides to use my SurfPI board and schematic that Silverdog has posted above then please be aware that it may contain errors. Also it must not be used for commercial gain without permission, it is copyrighted to me. I was hoping to tidy it up a bit before releasing it on the forum.
Regards, James.Comment
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