Archive for April, 2019:

2019-04-29 Center Tapped Voice Coil And OTL Circuit

from FB group Vintage Transistor Radios Apr 29 Robert Abend Yeah, thanks for bringing that up. Many of the GE radios have a center tapped coil in their armature speakers. I never really thought about the unusual CT voice coil. The most important reason why is that a voice coil moves and has to be

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2019-04-28 Samsung TV Remote Not Fully Functional

also FB group Building Transistor Radios 2019 Apr 28 Joe Curtis A few months ago I also bought a remote for my Samsung TV. It looked identical to my original, and the best thing about it was it’s just for Samsung so there is no setup hassles when batteries are put in – just point

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2019-04-27 VoIP Phone Trunks

from FB group Bell Telephone.. 2019 Apr 27 Mason Lepore One other point: virtual circuits are not like POTS lines. An incoming call is not like it’s on a dedicated line. I think about it like part of the central office has been moved to the customers’ location. There are trunks from the real CO,

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2019-04-26 Fake 14 AWG Speaker Wire

I got this 10 Amp power supply, so I wanted to make some heavy duty cables for it. I found that Walmart sold 50 feet of 14 AWG speaker wire for less than $20. I got it today, and after I stripped off the insulation, I thought that the stranded wire was much smaller than

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2019-04-25 Philco History

from FB group Vintage Transistor Radios April 26 I was always curious why Philips didn’t use their brand name in the US. Now I know. From wikipedia.org/wiki/Philco “The company (as well as the Sylvania brand name) was acquired from GTE by Philips in 1981 so that Philips could gain the rights to use its trademark

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2019-04-24 Optical Lighting Illusion

The first photo is a piece of wire rope covered with a colored plastic tube, illuminated by a blue LED. It looks like a mustard yellow to the eye. The second photo is the same exact piece, illuminated by the camera flash. It’s remarkable how much difference the light makes. It’s like night and day.

2019-04-21 Adjustable Switching Power Supply RFI Suppression

I’ve been experimenting with a switching power supply I got for $51.00, Model QW-MS3010D. It puts out 0 to 30VDC at 0 to 10 amps, adjustable voltage and current limiting. As would be expected, it puts out a lot of RF interference. I’m using an old Motorola AM radio as the receiver. I set the

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2019-04-20 DC to DC Converter for Tube B+

from FB group Building Transistor Radios Jon Edwards I’ve built a lot of JTs, they are useful for low power, under 100 mW. I got about 50% efficiency. What you have to do is make sure the reverse voltage emitter to base doesn’t exceed 5V, so it doesn’t waste power. A better way is to

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2019-04-18 We Take A Risk Every Time We Touch A Wire

from FB group Bell Telephone of… Apr 21 Jim Engle One time I was connecting up a POTS modem line and I was getting the crossconnect wire into the 66 block ready to punch them down. BRZZAP! I got zapped by the AC! Some idjit plugged a three prong plug into a 2 prong ungrounded

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2019-04-13 Olympus Digital Player Has Flutter

from FB group Vintage Electronics Test Equipment For… Apr 13 I see a Leader wow and flutter meter for sale. This reminded me of a problem I’m having with my Olympus digital recorder/player (WS-822, IIRC). I’m listening to it playing and it’s sounding like there is flutter in the music! That seems crazy to me,

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