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Mohican question, capacitors.
01-23-2016, 07:55 AM
Post: #43
RE: Mohican question, capacitors.
To complement what Katie have said:

Looking into the page 12 of the schematics indicated by Dave, we have the following eight electrolytic caps:

AVC (aka AGC) automatic volume control (page 8) and RF OSCillator stage (page 7)
- 2 x 10uF at 10V (C27 and C48 in the schema)

Power supply lines decoupling and filtering (page 9):
- 1 x 100-100-100uF at 15V -> this is a can with 3 caps, each one of 100uF at 15V. (C56, C57, C58)

Audio amplifier and output power stages (page 9):
- 2 x 50uF at 15V (C54 and C59)
- 1 x 150uF at 15V (C55)

This would sum up to a total of 8 polarized caps.

Concerning their capacitance values, electrolytic caps have an extremely high variance, even for recent production. Minus 20% and plus 50% are common and should not be an issue.

Some of the specified values are not standard anymore.
50 uF can be replaced with the now standard value of 47uF.
Concerning the working voltages, 15V should be replaced by 16V or higher.

Concerning the power supply:
It is positive ground. Why?
Because those Germanium PNP transistors have their emitter connected to ground (through a bias resistor which is AC bypassed by caps).
A PNP transistor operates with a positive voltage applied to the emitter (E) in respect to its collector (C).

Jose Mesquita
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Messages In This Thread
RE: Oscilliscope question - Garth Wilson - 01-21-2016, 05:49 AM
RE: Oscilliscope question - walter b - 01-21-2016, 09:55 AM
RE: Oscilliscope question - jebem - 01-21-2016, 05:16 PM
RE: Oscilliscope question - rprosperi - 01-21-2016, 11:51 PM
RE: Oscilliscope question - Steve Simpkin - 01-22-2016, 04:15 AM
RE: Oscilliscope question - jebem - 01-21-2016, 06:27 PM
RE: Oscilliscope question - Garth Wilson - 01-22-2016, 02:10 AM
RE: Oscilliscope question - vk6ti - 01-22-2016, 09:30 AM
RE: Oscilliscope question - jebem - 01-22-2016, 10:29 AM
RE: Oscilliscope question - jebem - 01-22-2016, 08:46 PM
RE: Mohican question, capacitors. - vk6ti - 01-23-2016, 12:14 AM
RE: Mohican question, capacitors. - jebem - 01-23-2016 07:55 AM
RE: Mohican question, capacitors. - jebem - 01-23-2016, 07:53 PM



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