Archive for the ‘Mechanical devices’ Category:

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

2018-08-03 GE Special Speaker And Iron Particles

From FB group Building Transistor Radios, Aug 6 This also happens with the meter movements of old analog meters. The iron particles get into the magnet assembly and stop the coil from moving. The only way I’ve found that gets rid of the iron particles is to very gently put a thin piece of steel

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2018-08-29 High Temperature And Nylon Screws

From FB group Hobby Electronics, 2018-09-01 I faced this dilemma before. I’ve repaired power supplies where the transistor failed because it was not held tightly to the heat sink because of a nylon screw that got hot. I used a steel screw and a fiber washer, and heat shrink tubing over the threads to insulate.

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2017-11-04 Zenith Royal 500 Fixed Part Way

I got another Zenith Royal 500 at auction, I think it was $20 but the shipping cost a lot.  I got it out and tried it out.  I found the battery contacts were in good condition.  The battery compartment was missing the cover.  It came with a leather case, so that will stop the batteries

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2017-01-18 Simulating An Analog Meter

A detector or discriminator in an electronic device might need to be adjusted to a very few points on a scale of a hundred or more points.  A digital indicator typically indicates only a fraction of that, possibly 16 points.  This is why the analog meter is still useful: it can indicate a small change

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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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2016-11-25 Screw Hole Photo

I cut a piece of plywood and very neatly exposed a screw hole, and I thought it would make an interesting photo. The screw was small, a #4 sheet metal screw about a half inch long. I had to used a magnifying glass lens to get a closeup.

2016-05-21 Monocular Mount For Phone Camera

I went through something like this last year, and I looked around online for something to solve the problem.  But I came to the conclusion that I didn’t like almost all of them for one reason or another.  Usually it was due to cheap, flimsy plastic.  So I began again with the intent to solve

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