Archive for the ‘Transmitter’ Category:

2019-01-15 2nd FM Microphone Kit Assembled

I ordered some other FM Microphone kits, and assembled one last week. This is a better one, labeled EEQKIT RF-02FM VER170525. It has three transistors, one of which is a microphone preamp and it should perform much better. The kit also has a jack that will allow you to plug in a stereo signal from

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2019-01-08 99 Cent Wireless Microphone Kit Assembly

2018-01-08 also FB group Building Transistor Radios Before the Xmas holidays I ordered a few of these at 99 cents apiece, and they gave a delivery date of late Jan to early Feb, so I was pleasantly surprised to get them early. There are many of these single transistor microphones around, either as schematics or

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2018-11-17 Cause Of Bleedover From Radio Stations

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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2018-09-28 LM386 Used As Modulator of Final RF Output

From FB group Building Transistor Radios 2018-09-28 I see nothing wrong with using the ‘386 to directly drive the power output stage. It’s cheaper than a transformer. But I was thinking about how the current was flowing in the ‘386’s output transistors. Normally an electrolytic capacitor blocks any DC from flowing out of pin 5.

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2018-01-08 RF Oscillator For AM Band

For FB group Building Transistor Radios When I started building regen receivers, the first thing I found I needed was a simple  signal generator.  I have a function generator, but every time I want a different frequency, I had to readjust the controls.  So I built a few RF oscillators to put close to the

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2017-12-03 AM Oscillator Instead Of Aux Input

From FB group Vintage Transistor Radios  For the last few months, ever since I started experimenting with oscillators on the AM broadcast band, my attitude towards auxiliary audio inputs has changed.  Earlier I thought  that it would be convenient to have an aux input.  But I was leery of making changes to the collectibles radio

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2017-06-02 I Built Another Oscillator For AM BCB

I pulled a pill bottle out of my junk box, it had a single layer of solid enameled wire wound on it, and it measured 85 microhenrys.  So I added the transistor, resistors and the capacitors to get it to oscillate at the low end of the AM BCB, around 540 kHz. The schem is

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2017-01-15 Tuned Circuit Tester

I’m building a tuned circuit tester, which is a Franklin Oscillator without the parallel tuned circuit.  I based it on the schematic I found at this URL.  The first amp is a JFET in common drain or source follower configuration, which then drives the 2nd stage, a PNP transistor in common base configuration, so there

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2016-09-29 FM Quality Stereo Tx

When I googled I found a ‘stereo input’ FM transmitter. Most of the FM ‘bugs’ on the web and YouTube have a microphone.  The circuit I linked to has left and right inputs, but mixes them to make a monophonic (not stereo) signal.  After looking at the schematic I noticed a mistake, so I thought

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2014-01-13 Coil For FM Microphone

I think I built one of these years ago but it must be buried in a box somewhere, probably in a pile of boxes in the garage. It’s a FM microphone transmitter, of which I have several, built from kits and from scratch. But this one was unique in that I built it with a

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