Archive for the ‘Electromechanical’ 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

2020-01-02 Coax Cable and Crimp-On Connectors

FB comment Years ago at work (community college) we had an IBM mainframe and the terminals were connected with coax cables. We also had thin Ethernet cabling. I had the proper connectors and thousand foot boxes of coax, and most importantly the proper stripping and crimping tools. I installed hundreds of coaxes, and I was

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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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2017-09-19 Giant ‘Analog Meter’ For Clock Display¬†

FB comment “Brilliant!” Preet Sangha said, and I agree, but since I have a hard time seeing small meters across the room, I thought up another, bigger meter.  How about this? Instead of meters, use a printout of a meter face, full page size.  There will be one for each hour, minute and second.  These

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2017-09-10 How Long Can An Arduino Circuit Last?

My answer to a FB Arduino group question on Sept 17 Dan Rogers has the right idea.  The protoboard, with all the holes in it, was never meant to be permanent.  The contacts in each hole lose their springiness as they are used to hold wires.  The contacts can become intermittent after awhile.  As time

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2017-06-04 Making A NC Switch Look NO

I’ve been thinking about this for awhile.  Let’s say I have a switch, for example a thermal switch that only has contacts that are NC (normally closed) until a certain temperature is reached.  At that point, it changes to open, interrupting the circuit.  But the input to my controller senses NO (normally open) switch contacts

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