Archive for the ‘Uncategorized’ Category:

2020-01-16 How To Remove Battery Corrosion

I took a battery holder that was corroded by leaking alkaline cells and I put it in a cup of vinegar. After several hours it came out clean, and I washed it off and let it dry. It looks pretty good now.

2020-01-08 Sorting Transistors Compared to Picking Fruit

I started thinking about how the makers of transistors sort the different grades of transistors as they’re manufactured. I thought that a reasonable analogy would be similar to how a farmer might sort the fruit he harvests. Here’s what I came up with.The farmer starts with the fruit his workers have gathered.  The fruit is

(Read More…)

2020-01-06 Two Similar Transistor Radios

I posted this a few days ago. Now I’ve replaced the capacitors in another one very similar, a DE LUXE. It’s not quite as complete and in as good a shape as the Encore. What surprised me was that some of the electrolytic capacitors were bad (measured open) and the symptom was no sound whatsoever

(Read More…)

2019-12-30 Plata 7 Transistor AM Radio Repair

From FB group Vintage Transistor Radios I rehabilitated this Plata 7 transistor AM radio made by Shirasuna Denki in Japan. I replaced the electrolytic capacitors, and I found that one of the germanium output transistors was shorted. I replaced both with silicon PNP transistors (the screwdriver tip on the right points to the two). Above

(Read More…)

2019-12-25 PSO Phase Shift Oscillator On Youtube

Merry Christmas… From FB … Dec 24 I found the video I watched and built the circuit a while ago. This is a PSO, phase shift oscillator. If you look at the wiki for a PSO you will see that it typically has three CR elements to shift the phase (the last is a combination

(Read More…)

2018-11-29 Fixing Badly Worn Volume Controls

from FB group Building Transistor Radios 2018-11-30 I’ve done some experimenting on volume controls that are badly worn and noisy. The idea is to substitute some resistance for the badly worn spot. The loud crackling will be reduced and the normal volume point will be moved to a higher point on the control. For a

(Read More…)

2018-11-26 Two 6 uH RF Chokes

from FB group Building Transistor Radios 2018-11-26 Two 6 uH RF chokes The photo shows two different RF chokes, each about 6.4 microhenrys. The one on the left is a ferrite bead, made by Fair-Rite, Cat. # 2643000801. These were about 12 cents apiece from Yes, the wire passes through the small hole

(Read More…)

2018-11-25 One Transistor FM Receiver Schematic Part 1

From FB group Building Transistor Radios Larry Daniel 2018-11-26 This is the original schematic posted by Larry. GM is a gimmick capacitor made of two short lengths of solid hookup wire, twisted together for a few pF capacitance. List of RF Chokes for the ham bands Larry said he used an RCA SK1008, then corrected

(Read More…)

2018-11-24 The Rise Of The PCs

from FB group Vintage Transistor Radios 2018-11-24 Early on, I built and upgraded many PCs when they became popular. Some for myself and friends, but most at work. Before that I was maintaining and repairing terminals and other equipment attached to mainframe computers. It started out small with TRS-80s and Apples but really took off

(Read More…)

2018-11-22 Homemade 9 pF Gimmick Capacitor

Also posted to FB group Building Transistor Radios Watson’s 9 picofarad homemade “gimmick” capacitor This homemade capacitor can be used for circuits were the capacitance is not critical, such as a wireless microphone for the FM broadcast band. The wire can be obtained from the cable used to connect telephone outlets. Solid (not stranded) plastic

(Read More…)

© RustyBolt.Info/wordpress