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
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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
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from FB group Bell Telephone… 2018-11-22 Happy Turkey day! I use solder all the time, and I trust it as long as it’s done properly. But one thing I learned in my decades of telephone work is that the wiring systems the telcos developed were tested and proven before they were deployed, and they were
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from FB group Building Transistor Radios 2018-11-19 I shared my loop antenna – see photo, and it is somewhat 2 dimensional. The arms are 762mm across but the depth of the windings is only about 35 mm. Compare that to the ferrite loopstick at the other extreme, it’s 10 mm diameter but 100 mm long.
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from FB group Building Transistor Radios 2018-11-19 IMPORTANT I used to work for a guy who did radio engineering and would troubleshoot problems such as this ‘bleedover’. For convenience some radio stations colocate their transmitters near or at the same site. Because the signal strengths are very high, the two stations can cross modulate their
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From FB group Building Transistor Radios 2018-11-19 Garry Heard I’ve found that a problem with using electrolytic capacitors to filter out the RF noise is their internal ESR, effective series resistance. They don’t filter out the RFI as good as they should. I found that MLCCs do a better job, if I used some multi
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from FB group Building Transistor Radios 2018-11-19 Bob Johansen I worked at a company that had ESD mats on the workbenches, about 1980. We had wrist straps with a 1 Meg resistor in series with the cord to prevent shock hazard. I found that the leads of the resistors were broken but the heat shrink
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from FB group Building Transistor Radios 2018 Nov 7 I bought some 10 uF, 10 volt MLCC (multilayer ceramic capacitor) capacitors, which do not have the electrolyte so they can’t dry out. They are smaller, too. If they are used for replacements, then radios might last much longer. About the only thing left to go
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From FB group Building Transistor Radios 2018-10-26 I repaired a lot of old tube TVs, and I saw that the repairs were dying when it was cheaper to remove the chassis from the old TV’s beautiful wood cabinet and buy a new cheap TV and put it into the wood cabinet. It even had a
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from FB group Building Transistor Radios comment 2018-10-08 Bob JohansenReceive frequency? I can’t receive a signal, so the receive frequency is not known. This receiver has no tuned circuit in the RF side of the NE612, other than the bandpass filter made up of the coils on the PCB and their capacitors. The bandpass is
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