Archive for the ‘Capacitors’ Category:

2020-06-13 MLCC Replacements For Electrolytic Capacitors

Reply from FB comment Mark French I got a roll (on tape) of 22 uF, 10V and 47 uF, 10V tiny surface mount MLCCs. They’re not polarized, but I’ve heard they tend to be microphonic. I’m going to try leaving the old caps in and bridge a MLCC across them. They’re small enough to to

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2020-01-23 DIY Variable Capacitor 90 to 3400 pF

The beginning isn’t clear about how it looks. First, scroll to end and look at the photo. https://www.randombio.com/capacitor.html

2018-07-20 My Digital Dice Were Loaded!

From FB group Building Transistor Radios, Jul 27 Rolando Fernández I bought a kit for a digital die (one die of a pair of dice). I assembled it and then I rolled the die many times and wrote down the values to see if it was random. I was shocked! It was loaded! It was

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2018-01-01 H N Y! Old Germanium Transistors Lose Gain As They Age

Happy New Year! I replied to a comment by George Glavas on FB group Vintage Transistor Radios George Glavas I’ve never read any documents to back up your claim that “…germanium transistors lose gain as they age.”  I think that people believe this because old equipment has lost gain.  But all of the problems I’ve

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2017-12-15  Royal 500 Capacitors Replaced

From FB group Electronics Hobbyists, regarding the Zenith Royal 500 radios. Clyde Hendrickson  There are two 50 uF, 10V electrolytic capacitors under the battery holder.  Replace them with 47 uF, 10 or 16 volts. There is also a smaller capacitor next to the other, it might be a 3 uF, or a 16 uF, 10V.

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2017-08-07 Protoboards And Bypass Capacitors

From FB post One important thing that people forget to do is consider what might happen with a circuit that has anything that draws power from the protoboard. If you’re working with a few low power devices such as small LEDs and switches, then there is usually not a problem. But if you have a

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2017-06-15 Capacitor Leakage Tester Ideas

I was asking about very old capacitors and their shelf life on FB vintage test equipment group.  The guys tell how good the old capacitor testers are because they have the “magic eye” to check for leakage. I was thinking that it would be easy to test any capacitor for leakage.  All that’s needed is

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2016-12-05 Regenerative Receiver

After I unsoldered the parts from my failed ‘noisy regenerative receiver’ circuit, I decided to build a more conventional regenerative receiver, one that uses a single transistor for the regenerative stage. I chose the circuit from a website that I had found, and saved the schematic. But I forgot to document the URL of the

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2016-08-20 Blue Blinky Gets A Different Timing Capacitor

It has been a long time since I designed Blue Blinky; I just wanted to update it.  I have used a 1 uF electrolytic capacitor for the timing capacitor, and it works just fine with the two 680k resistors to give about 1 per second flash rate. I got a bag of hundreds of multilayer

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2016-04-18 Coil For FM Microphone Bug Transmitter

I’ve built an FM microphone bug or transmitter before, but it’s been a very long time since I wound coils for one.  Long ago I would wind too many turns on the coil and try it out.  The usual outcome was the bug would be transmitting somewhere in the low TV channels 5 or 6,

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