Oops! (posted to FB groups) A Wien Bridge Oscillator that’s not a bridge. It’s missing the negative feedback side of the bridge! That must mean that the amplitude of the sine wave changes with changes in the temperature, supply voltage, and other conditions. Not a good design! http://www.seekic.com/circuit_diagram/Signal_Processing/Oscillator_Circuit/WIEN_BRIDGE_OSCILLATOR_I.html
Archive for the ‘Uncategorized’ Category:
2017-05-24 DECWriter LA-36
From a comment I posted to FB Vintage Test Equipment group. I’m looking for some parts for a DEC DECWriter LA-36. The model I have has the acoustic modem behind the paper feed. I’m also interested in other parts. If there are others who have this big, heavy printer, I also have some manuals for
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2017-05-17 Lamp In Audio Oscillator
This is from a FB comment by me. Speaking of audio signal generators, I made an audio signal generator, the classic Wien Bridge oscillator with the lamp, in my case it was a 28 volt low current lamp, I believe an 1869. Well I got the lamps from Radio Shack, and the circuit had an
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2017-05-09
At work I had a Fluke 8040(?) that had the LCD tilted up. Worked great, but after a half dozen years we had so many terminals in (and out of) service that I couldn’t spend as much time troubleshooting, and since Lear Siegler was less than a dozen miles away, we just bought enough spares
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2017-05-05 27 Mhz Signal Generator Continued
This continues the updates from my blog of 2017-04-21. Last night was the fifth of May, and I made several important changes to the circuit. I was finding that after adjusting the 8 to 50 pF N150 ceramic variable capacitor, the frequency would drift for hours, then overnight the drift would settle down to a low
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2017-05-05 Field Strength Meter Schematic Error
From my post to FB groups Well, here’s another circuit that’s doubtful that it works. It looks to me that the 22n capacitor bypasses the amplified RF to ground so the diodes can’t rectify any RF. If there was a 1 to 10k resistor between the diodes and 22n capacitor, then I could be persuaded
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2017-04-27 Superregen FM BCB Receiver
I built this superregenerative FM broadcast band receiver today. This circuit is similar to the one I posted on January 22. Here is a list of parts values I used: ANT – 12 cm insulated wire connected through 10 pF capacitor to FET source. C4 – two 2.2 nF MLCCs from + to ground plane (
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2017-04-23 Linear Power Supply Renovation
In the past I’ve built several of these small power supplies to use around the house, and they come in handy. But those others used a 12 VAC transformer instead of an AC adapter, so I had to add a fuse and other stuff to prevent shock. Using the AC adapter is much more convenient
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2017-04-21 Signal Generator for 27 MHz
I need a source of signals on various frequencies to test how well my bandpass filters are aligned. I built a Vackar Oscillator with tuning over a few CB channels, mainly 27.095 to 27.255 MHz. These are radio control frequencies. Like a Colpitts oscillator, the Vackar’s resonant circuit has two capacitors in series with the
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2017-04-20 27.145 MHz Transmitter And Receiver Pt 1
I’m trying to make a simple wireless alarm link. The transmitter will be in an unheated garage, so the only way to easily get it to stay within the -+ 10kHz channel will be to use a XO (crystal oscillator). But for the receiver, I figured the best way to go would be to
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