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Re: AGC Circuit for uBITX Featured in July 2019 QST Magazine


 

All caps have a rated voltage. That is the max voltage you apply to it. If you exceed this voltage the insulation between the "plates" of the cap will break down and the magical smoke will be released out of it. It will blow. Alliminium? caps are very sensitive to this max voltage. Therefore the max voltages are printed on them so you are can be aware of it. And the circuit designer also jods it down on the cct diagram. If your supply voltage is say 12V, it is safe to use a 16V rated cap. You do then have a safety margin for 'n slight mishap in the supply voltage if it occur. The cap will only charge up to the supply voltage. So using a higher voltage rated cap will make no difference. The cap can not generate a higher voltage than what is supplied to it. Your safety margin will just be greater. Using a 50V cap in a 12V system ? So what. The capacitance of the cap is worth watching and to adhere to. Also the voltage rating of the cap determines its fiscall? dimensions.?

J van der Merwe

On Mon, 12 Aug 2019, 12:21 David Wilcox via Groups.Io <Djwilcox01=[email protected]> wrote:
Can someone explain the reasons for certain voltages listed on any schematic for the electrolytic caps, AND what problems could arise if one used a cap with a larger voltage rating? How much higher a voltage cap could be substituted without causing a problem?

Dave K8WPE?

David J. Wilcox K8WPE¡¯s iPad

On Aug 12, 2019, at 2:18 AM, MadRadioModder <madradiomodder@...> wrote:

Since the entire circuit set is 12V or less, your 16V caps should work just fine.

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From: [email protected] [mailto:[email protected]] On Behalf Of Rob French (KC4UPR)
Sent: Monday, August 12, 2019 12:40 AM
To: [email protected]
Subject: Re: [BITX20] AGC Circuit for uBITX Featured in July 2019 QST Magazine

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Thanks.? Any thoughts on voltage rating for the capacitors, especially the "big" electrolytic ones?? (10uF, 100uF, 470uF... I'm assuming they're electrolytics.)? I looked at the Hycas schematic, and that calls out 50v for all the caps, but I don't have many of those... got lots of 16v though!


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