Archive for February, 2019:

2019-02-19 Transistor Tester & Running From Single AA Cell

from FB group Building transistor radios 2019 Feb 19 I use a wall wart on mine. It’s a 6VDC regulated output. The tester says battery is low (it expects 7 to 9V) but it still works okay. I have a few of these, it uses a microcontroller. Notice that it runs using a single AA

(Read More…)

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

(Read More…)

2019-02-12 FM Microphone Schematic and Parts Placement

I got three of these no name, unbranded kits from a seller on eBay. The kit comes with all parts and a PC board, but the labels on the board are R1, R2, R3… but no values for the parts. There is a schematic and photo of the completed board, but the schematic has no

(Read More…)

2019-02-11 The College IT Datacomm System

from FB group Bell Telephone… 2018-02-12 After the early ’80s when the RBOCs created the MPOE, all their wiring on campus became ours, and we never got any records from them of what was in the ground. On top of that we had a contractor come and install gel filled telephone cable along with ITV

(Read More…)

2019-02-10 Parallel Resistors Made Easy

Something that should be memorized by every technician. This also applies to capacitors in series.

2019-02-09 AA5 OPTs And Winding

from FB group Building transistor radios All the AA5 single ended OPTs I’ve taken apart have had the ‘air gap’ which is really a piece of paper. I presume that is because the DC current magnetized the core and if it didn’t have the gap it would saturate and have a lot of distortion. I

(Read More…)

2019-02-08 Solenoid Used To Switch a Toggle Switch

from FB group Building transistor radios Feb 11 Cool! I found one circuit that used a neat trick. They put a large value electrolytic in series with the coil, and a low value power resistor across the capacitor. When the coil is energized the full current goes through the coil until the capacitor is charged,

(Read More…)

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,

(Read More…)

2019-02-04 Fukushima Daiichi Nuclear Power Plants

In the years since 2011 Mar 11, I have blogged a few times about Fukushima Daiichi, but it’s been quite awhile. This ABC Nightline video on YouTube seems to be realistic and relatively unbiased. At the end of this video they mentioned $15 Billion and forty years to do the cleanup. It looks like they

(Read More…)


from FB group Orange Talk 2019-02-05 Bora Han Proko Many years ago, a Japanese organization bought or was supposed to buy the land on the corner of Main Street and Memory lane where Polly’s Pies used to be and where Mother’s Market is today. The economy went down and the big plans didn’t work out,

(Read More…)

© RustyBolt.Info/wordpress