OPIC Microphone (Basic PCB) can helps pls ?

[mic test]

hello I have a problem I have tried everything I can't get the plate to work how do I connect the two boards together pin 1 xlr1 pin2 xlr 2
Pin 3 XLR 3 and how is the XLR cable connected at the bottom of the board or in the middle this is the parts list

part one

1​	CD40106​	U2​	CD40106BM96E4​
1​	Z12​	ZD1​	TZX12D-TR​
7​	1N4148​	D1,D2,D3,D4,D5,D6,D7​	​
2​	10k​	R11,R14​	​
2​	27k​	R12,R13​	​
1​	var.​	R15​	refer to Rogers information I took a 1Kohm 5% Is that right?​
1​	1n​	C11​	K102K15X7RH5TL2​
6​	0,01µ​	C13,C14,C15,C16,C17,C18​	K103K15X7RH5TL2​
3​	0,1µ​	C19,C20,C12​	K104K20X7RH5TL2​
1​	47µ​	C21​	710-860040572002​
part 2 1​ OPA1641​ U1​ 595-OPA1641AID​ 1​ 1G​ R1​ ​ 2​ 47R​ R2,R3​ ​ 2​ 10k​ R4,R5​ ​ 2​ 47k​ R6,R7​ ​ 2​ 0,1µ​ C5,C6​ 505-MKS2C031001AJC00​ 2​ 0,01µ​ C7,C8​ 505-MKS2C021001AJI00​ 4​ 47µ​ C1,C2,C3,C4​ UFG1J470MPM​ Where can I measure to see how many volts I am a beginner please understand ​	​	​	​

 

[rogs]

I have only built one mic using Mic Scharf's PCBs, and that was a multi-pattern version (for most of my builds I use stripboard).
The results should be the same as the original stripboard versions though.

• I don't know what you mean by getting the 'plate' to work ? (something lost in translation, I suspect).

• The XLR connections - 1, 2 & 3 - on each board are simply connected to the corresponding pins on the male XLR connector, fitted into the mic body.
For connecting to both PCBs, I find it easier to twist the stripped ends of 3 pairs of short lengths of 10 x 0.1 equipment wire.
Solder the twisted ends to the XLR socket, and take two separate 3 wire leads, and solder one set one to the marked connection points on each board.

I see the VM board has 2 sets of connections, so you could take the connections from the XLR plug to that board, and then take short leads to the second connections on that PCB to the main PCB. Either way should work OK.

• Regarding the voltages, I'm not sure if Mic Scharf has prepared any separate documention to describe the details of his PCBs - I've not seen any myself?

You might find the circuit descriptions for the original design useful -
You can find those by scrolling down this document : https://www.jp137.com/lts/OPIC.41.pdf

• The circuits are the same for both projects -- you may have to check the component ident numbers, which maybe different on the PCBs, but hopefully that shouldn't be too difficult.

You'll find the kind of voltages you should be getting at various points, in those circuit descriptions.

 

[mic test]

Thanks a lot Rogs I saw that pin 3 shouldn't be connected to the board. That was very interesting at first. I had to bend the pin away. Now I get the signal but it sounds like it's buffering. It's pumping in the signal every 3-5 seconds be defective the capsule is new from aliexpress
Where else could it be? Upload a recording straight away

 

[mic test]

this right ?

 

[rogs]

this right ?

No -- the separation of pin 3 of the op-amp only applies to my stripboard layout, not to the version from Mic Scharf's PCBs.
This was to help keep the (very) high impedance connection between the 1 G resistor and pin 3 away from the stripboard.

In the case of tha PCB version all 8 pins of the op-amp should be connected. You'll see that there is a connection between pin 3 and the end of the R1 next to the edge of the board. That connection is also made to the capsule, via the 'Caps Sig' temination.

So it seems that Mic has decided that there is suffiecient spacing on the PCB to not cause any problems, and has no made any provision for any 'off board' connections to the 1G resistor (R1)
This should work fine, but you will need to ensure that the any flux surrounding the pin 3/ R1/ Caps Sig termination on the PCB is properly cleared.
Use Isoprop alcohol to clean that area thorughly.

 

[mic test]

thanks for help rogs OK, because the photo was as described by Mike, I thought I had to bend pin 3 up so that it wasn't connected to the board at that point and put a bridge to the capsule signal and put R 1, which was a bit confusing

 

[rogs]

thanks for help rogs OK, because the photo was as described by Mike, I thought I had to bend pin 3 up so that it wasn't connected to the board at that point and put a bridge to the capsule signal and put R 1, which was a bit confusing

I decided to not connect pin 3 to the stripboard, to reduce the possibiliy of nearby stripboard copper tracks causing problems at that impedance (stray capacitance, excess flux residue, etc)

I had no input to Mic's PC layout - he merely asked me if he could use my circuit.
I can see that he has allowed sufficient gaps in the track layouts so that - providing the excess flux is completely removed - there should be no problems with connecting both R1 and the op-amp pin3 directly to the PCB

 

[mic test]

OK, thank you very much, now I understand it, but I still have a problem. I get very little level and Apollo Twin 10db mic gain and I only get -46db signal level and the level sprints from -46 to -56. I don't know where the error could be

 

[rogs]

There is no gain from the OPIC circuit. It is simply an impedance convertor and unity gain buffer. The amount of signal output from the mic will depend on the sensitivity of the capsule and the level of the DC polarisation.

A simple way to check the circuitry is functioning correclty is to remove the capsule connection to the PCB.
Then solder one terminal of a small capacitor (value not critical) to that same connection point. The second wire can then be connected to a signal source ( a signal generator - or even the output of a music player will do).
You should then find that the level of the signal source itself and the output from pin 2 of the XLR should be pretty much the same.
If that is true, then the problem lies with the capsule or the polarisation voltage.

If it's not true then check the op-amp voltages....
You should find (around) 22v on pin 7, and half that on pin 6. That should be exactly half the value, if your bias resistors R6 and R7 are correctly fitted.
If those are not right, then there is either a faulty connection somewhere (solder bridge or dry joint ) or the op-amp itself is faulty.
Double check your solder connections before you replace the amp!

If the op-amp voltages are correct, but you still have no signal, it's likely to be something else..

It could be a capacitor fault ( faulty connection, or open or short circuit). Those last 2 are unlikely with new capacitors.

It's unlikely to be a resistor, if you have fitted the correct values.

If to have access to an oscilloscope then fault finding becomes easier.... you can signal trace on the PCB.

Without one, fault finding can be a bit of a lottery. Check all the solder connections again - and then again!

 

[mic test]

OK, I installed another capsule from another mic, the interference is gone, but I have to amplify it up to 39 dB in order to hear myself well. With the other microphone, I can hear myself very well at 0 dB amplification. There are 2 points on the board where I can I can measure to see if the 70 volts are present. I'll try it

 

[mic test]

View attachment fehler.mp3
Why does it make such a beeping noise? What could be the problem? What have I broken?

 

[rogs]

........ With the other microphone, I can hear myself very well at 0 dB amplification......

What is 'the other microphone' ?

(With regard to your last post, There's no audio file that I can find... )