Oscillators without transistors

The neon bulb thing only works because the bulb turns itself off abruptly at low voltage, then doesn't turn on again immediately as the voltage recovers. This hysteresis is why it works.

Other non-transistor, non-tube oscillators:

Electromechanical buzzers Mechanical clock balance wheels Coffee percolators Baseball cards in bike spokes Thermoacoustic refrigerators Dog whistles Ocarinas Blowing over a beer bottle Slinky going downstairs Bay of Fundy Internal combustion engine piston

Tunnel diode oscillator SCR relaxation oscillator

Cheers

Phil Hobbs

Negative resistance spark gap ?

High frequency alternator ? As I recall, Fessenden used a 100 KHz generator to transmit music and voice in 1906.

David

snipped-for-privacy@gmail.com wrote:

Tunnel diodes Gunn diodes

masers lasers spin-torque oscillators

When I was in high school I built this rather elaborate relay oscillator to dial a pulse type telephone. One relay developed pulses, another was rigged as a monostable to time the pulse train to dial a particular number. A rotary stepper relay could read the holes in cards and cycle through some crude punch cards to dial (worked but not well)

Scr's can be made to oscillate, of course unijunctions, some negative resistance diodes like tunnel/gunn, electro-mechanical toys using magnets and leaf/reed switches or transistors to energize coils, old-time magnetic earphones and carbon mikes to develop feedback, tuning forks with feedback drivers, propagation delay devices, arc lights, early radio transmitters that used motors driving many-pole alternators, spark-excited Tesla coils...

Ah ok, thanks. While I was at the university I was under the impression that one could create an oscillator with a combination of resistor, inductor and capacitor, but now I see most electronic oscillators require a transistor of some sort.

Michael

needs a gas discharge tube, spark gap, sidactor, tunnel diode, PUT, or UJT etc - something with a negative resistance region, LED won't work.

tesla coil. (and other spark gap oscillators)

car horn, dc electric bell (I guess these are really relay oscillators)

electric motor

hot-wire (wire heats up due to current and gets longer) eg: automotive blinker unit

bimetallic (metal changes shape in response to heat from an electric heat source) eg: stovetop simmerstat

carbon microphone feedback (I guess this is an accoustically coupled analogue relay oscillator)

Old style doorbell or buzzer.

And, of course, there are a range of purely chemical oscillators As good a starting point as any is

On Wednesday, October 17, 2018 at 7:32:04 PM UTC-7, snipped-for-privacy@gmail.com wrote :

tor

stor

The spin-torque oscillator is magic. It is a thin film structure with nano meter-thick layers of normal conductors, ferromagnetic materials, and antif erromagnetic materials. Apply a dc current, and it continuously produces m icrowave oscillations. No active gain elements or resonators are required.

There are also Gunn and IMPATT diode microwave oscillators.

Cheers

Phil Hobbs

Carbon microphone and speaker.

Pendulum clock.

Arc oscillator (once used for broadcast transmission)

Violin.

Clarinet.

Zener diode.

Gunn diode.

Fingernail on blackboard.

There used to be signs that used movement to get attention, it could be as simple as a waving hand. The hand was setup as a pendulum and when the battery was installed you could give it a push, this would close a switch, energizing the solenoid and giving the pendulum a kick this would also open the switch. The pendulum would go through its swing and then come back and close the switch, repeating the cycle. I searched but could not fid a sign or a circuit, but I'm sure there is one somewhere online. Variation of the relay oscillator.

Mikek

The vibrator in an old car radio. Not only does it oscillate without transistors or tubes, some rectify without diodes. A second set of contacts make for a synchronous rectifier.

If you ever opened one, you would find it is basically an electromagnet configured as a buzzer, just like the one you probably built in grade school science or shop class, and just like the one you mentioned a couple weeks ago.

Amazing!

How long did they last? A year or so?

Thanks!

Michael

The really fun one was the box with a trap door on top and a big toggle switch on the front. When you turned on the switch, a motor whirred and a plastic hand came out of the box, turned the switch off again, then went back into the box before the motor actually turned off.

I had a piggy bank that worked like that--you put the coin in a shallow slot with two contacts at the bottom. The coin completed the circuit, and the hand came out and collected the coin.

Cheers

Phil Hobbs

a car won't last a year if operated continuously: at 60 km/h that would be half a million kilometers

I had one in my car for a couple of years and never had a problem. that was maybe 400 operating hours.

I expect they got a couple of thousand hours out of those units about the same as we see quoted for cheap electrolytic capacitors and LEDs.