I am trying to copy a preamp circuit for an electrostatic transducer
pickup so I can make it stereo. It looks very simple, but there are
two little white blocks I cannot identify. One has a logo I don't
recognise and a number 022J400. The other says only 68nJ63. Are they
capacitors? If you want to see a jpeg, go to www.fotos.web.de/robobass
(You don't need to read German, just click on the folder icon at the
bottom left.) I have a Mouser catalog CD, but I'm not getting anywhere
just searching with these numbers. Does anyone know this logo?
Also, the transistors say BC 550B. Again, anyone know the brand?
Alsoalso, am I reading the resistor code (the wide brown band being
tolerance 1%) correctly?
My humble thanks!
Robobass

"robobass" wrote in message
om
I am trying to copy a preamp circuit for an electrostatic transducer
pickup so I can make it stereo. It looks very simple, but there are
two little white blocks I cannot identify. One has a logo I don't
recognise and a number 022J400. The other says only 68nJ63. Are they
capacitors? If you want to see a jpeg, go to www.fotos.web.de/robobass
(You don't need to read German, just click on the folder icon at the
bottom left.) I have a Mouser catalog CD, but I'm not getting anywhere
just searching with these numbers. Does anyone know this logo?
Also, the transistors say BC 550B. Again, anyone know the brand?
Alsoalso, am I reading the resistor code (the wide brown band being
tolerance 1%) correctly?

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robobass wrote:
I am trying to copy a preamp circuit for an electrostatic transducer
pickup so I can make it stereo. It looks very simple, but there are
two little white blocks I cannot identify. One has a logo I don't
recognise and a number 022J400. The other says only 68nJ63. Are they
capacitors?

They are 68 nF film caps rated for 63V operation.

If you want to see a jpeg, go to www.fotos.web.de/robobass
(You don't need to read German, just click on the folder icon at the
bottom left.) I have a Mouser catalog CD, but I'm not getting anywhere
just searching with these numbers. Does anyone know this logo?

I don't have any graphics. But check the Buerklin catalogue.

Also, the transistors say BC 550B. Again, anyone know the brand?

Doesn't matter, the Pro-Electron numbers are standardized for all of
the European manufacturers.

Unless you plan to use exactly the same parts and the same layout as the
original, I think you might want to just replace the existing electronics
with two channels of your own copy.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."