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Does anyone know of a modern capacitor with these values

marc11657

Oct 23, 2013
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I'm building a point to point circuit (so no PCB) but I'm struggling to source a capacitor with similar values on this schematic. Does anyone know of anywhere? I've tried Mouser and Farnell but no luck.

I'm looking for a capacitor with 20MMF 1.6kv

Thanks,

Marc
 

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duke37

Jan 9, 2011
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Thats a powerful beast you have there !

20MMF is an old way of expessing 20µµF or 20pF in todays money.
It may be difficult to get a 20pF capacitor so you could use two 10pF capacitors in parallel or use a 22pF capacitor. I do not think the value is critical.

The voltage rating may be difficult but some CRT televisions had disc ceramic capacitors suitable for high voltages.
 

marc11657

Oct 23, 2013
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Perfect! Thanks! And yes it is indeed a beast of a schematic! Possibly too big a beast for me to handle with my knowledge, but I'm giving it a good go anyway.

I've now made my shopping list for capacitors, resistors and tubes. I'm now looking at the diodes/rectifiers C101-C104 and C201-C20. My aim is to try and stay as close to the original design as possible. Do you have an idea of what sort of rectifier would have been used in those places?

The file is too large so I've got the full schematic on the site www.the-egg-recording-studio.com/670.jpg

Cheers!
 

duke37

Jan 9, 2011
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It is not easy to read the schematic.

The diodes are shown as 1N538. The data for these seems to vary. They may be 100V 250mA.They are available on Google.

I do not know what this thing does but if the frequency is not over, say, 10kHz then 1N4007 would be the cheapest when bought in bulk.
 

marc11657

Oct 23, 2013
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Thanks,

Yea I had the same trouble trying to figure out the exact values of the rectifier. Maybe there's a calculation I could do to work out the missing values?

It's a schematic for a 1950/60's recording studio compressor/limiter. I'll have a search around the net to see if there's any documents that hint towards the diodes values.

I've also just noticed there's another group of rectifiers down at the bottom labeled simply as CR301 without any model number at all!
 

duke37

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CR301 looks like a low voltage, low current bridge running at mains frequency. Four 1N4007 would romp away here.
 

davenn

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Sep 5, 2009
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The main rectifier is valve V301 ... this is producing the high voltage DC rail for the other tubes

I've also just noticed there's another group of rectifiers down at the bottom labeled simply as CR301 without any model number at all!

yes that one is just providing several negative rail voltages from a separate mains transformer

Dave
 
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