Archive for the ‘Electronic Components’ Category:

2019-02-16 The Old Time 2N708 Transistor Cartel

Left link to this on FB. I saw the Electronic Goldmine email ‘flyer’ ad for 2N708 transistors on sale so I had to order a bunch of those to experiment with. But their ad said nothing about them being NOS (new old stock). I’ve bought some junk from them before that were rejects or floor

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2019-02-05 Floating Detector Diodes Are Not A Good Design.

from FB group Building Transistor Radios 2019-02-05 Graeme Heal Aaron Cake has a lot of good circuits and projects. But this one uses the ‘floating detector diode’ with no DC return path, so the circuit will only work if the diode’s leakage current provides the discharge. That means the diode must be germanium, not silicon,

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2019-02-01 Raytheon 1N128 Germanium Diodes

Link left on FB group Building Transistor Radios Someone in the group mentioned a source of crystal radio parts, Small Bear Electronics and linked to their website. I found that they had some germanium diodes, Raytheon 1N128, and they showed the reel of them, so I thought my chances of getting factory parts would be

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2019-01-11 The 1N60P “Germanium” Diode Issue

From FB group Markku Vuorensivu I bought some 1N60P “germanium” diodes and I found they are not germanium, they are Schottky silicon diodes. They do not work like germanium diodes in circuits that depend on the leakage that germanium diodes have. The Schottky or germanium diodes can be checked for reverse leakage and germanium will

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2019-01-10 The Ninth Anniversary Of The Philips LED Candelabra Lamp

On Jan 11, 2010 I connected a Philips candelabra lamp to the AC line and turned it on, and for the last nine years it has been running continually, except for a few days time when the power was out, which might add up to a few days, probably less than a week. I did

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2019-01-05 Substituting Chokes For A Coil In A Reflex Circuit

From FB group Building Transistor Radios 2018-01-15 Nick wants to use two 10 mH chokes close to each other in place of a coil that’s used in the typical reflex circuit. I’ll include a schematic of the circuit (from somewhere on the net). This is labeled L2. (begin my comment) Nick Bastian The coupling is

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2018-12-31 Zenith Royal 500 Unique Issue

Also to FB group Building Transistor Radios 2018-12-31 I have several Zenith Royal 500 radios with the ‘long range’ eighth transistor added as a RF preamplifier (chassis number begins with 8). See the attached photo. This does not require a third section on the tuning capacitor, as some ‘TRF’ radios have. Zenith added a tuned

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2018-12-12 LM78xx Linear Regulator Disadvantages

from FB group Building Transistor Radios 2018-12-13 Joseph Rotello I agree with some of your claims. But I know far more about 3-terminal regulators than you think. First off, your claim that they are more efficient is unproveable. There are linear PSes that are more efficient. That was the reason LDO regulators were used. You

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2018 Dec 8 Sinclair Book 22 Tested Circuits Using Micro Alloy Transistors

from FB group Building Transistor Radios 2018 Dec 8 Nick Bastian posted the schematic of a Sinclair Micromatic radio. I found the book by Clive Sinclair about the circuits using micro alloy transistors. Germanium transistors and especially micro alloy transistors are no longer made so it’s better to use silicon BJTs instead. Here is the

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2018-12-04 FETs For Very Low Voltage Joule Thiefs

from FB group Building Transistor Radios 2018 Dec 4 Terry Harris I didn’t try to mimic the ALD, I used the FETs for a voltage booster. The typical 5mm LED needs somewhere around 60 mW for Max brightness. If I was powering it with 60 millivolts, it would require over an amp to get the

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