Archive for July, 2017:

2017-07-31 Transistor Radio Repair List Of Problems

2017-07-31 from FB reply by Phillip Grace The worst is damage from leaking batteries and flood damage. The latter isn’t always apparent at first until you open up the set and find signs of sediment or corrosion. Common problems are of course failed capacitors, physical damage, and bad/failed repair attempts and tampering. Taken care of,

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2017-07-27 Laptop Charger

from FB reply 2017_07_27  Richard Robertson Look at this schematic of a typical laptop charger.  Notice that the left side has the two pins of the power plug.  They are not polarized, and may be inserted into the socket either way.  No pin for ‘ground’ or ‘earth’ is shown.  Notice that the ‘ground’ or ‘earth’

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2017-07-16 tbd


2017-07-13 Don’t Use Your Original Remote Control 

From FB reply My remotes seem to go bad all the time.  Batteries low or dead, battery juice leaking on the circuit board, broken wires from falling off the table, getting sticky or worn, etc.  I try to minimize the wear and tear on the original remote.  I never use the original remote, I use a cheap

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2017-07-14 Underwater Speaker

From a reply on FB I built a speaker for a swimming pool.  It was a large can of steel with an audio transformer mounted inside.  The ‘I’ laminations were removed so the ‘E’ laminations could be very close to the end.  I drove it with a 2N3055 on a heatsink.  The secondary winding must

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2017-07-15 Appliance Light To Limit Current

Reply to a FB comment about using an incandescent light in series with a repaired equipment to limit the current when it’s first turned on. You can still get incandescent lights around 40W, but they are called appliance lights.  You can’t expect a LED light to work in a dryer or oven.  Also there are

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2017-07-12 It Worked!  Arduino Pro Mini Programmed

This homemade PS is smaller than an ATX PS, but the best thing is it’s quieter, because no fan is runningThis homemade PS is smaller than an ATX PS, but the best thing is it’s quieter, because no fan is running.

2017-07-10 Burgess Battery In Old SCR RADAR Set

I took an electronic technician class at Compton College back in ’66, and the teacher gave us an assignment to work on the antique SCR RADAR sitting outside the classroom.  We found that the antenna would rotate but it wouldn’t transmit.  We had the schematics and diagrams for it, so I started looking for some

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2017-07-09 Microcontroller For Monitoring Solar And Leg Power

I’ve thought about using a DC motor as a generator to charge a super capacitor or battery, using human (leg) power.  If I get an exercise bike, I would like it to do some useful work.  Say, connect the capacitors or battery to a DC to DC converter to make 5V to charge my cellphone.

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2017-07-08 Charge Phone from 12V Solar Panel Using SMPS

The guy in FB group asked how to charge his 5VDC phone with a 12V solar panel.  Several others said to use a 7805 V regulator to drop the 12VDC down to 5VDC.  This will do the job, but I told them that the 7805 wastes most of the power as heat, and only a

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