Get oscillator

[chucksue]

I’ve searched the internet looking for a circuit using FETs to make a mono stable oscillator. I want it to drive the primary of a transformer at 200 hz. This is for the old car radios that used a mechanical vibrator . Any help and ideas

 

[bertus]

Hello,

You could have a look at this circuit and adapt the frequency:

https://www.researchgate.net/figure/Circuit-diagram-of-MOSFET-based-oscillatory-circuit_fig3_332332621

Bertus

 

[danadak]

Voltage Regulator oscillator :

Regards, Dana.

 

[ramussons]

Hello,

You could have a look at this circuit and adapt the frequency:

https://www.researchgate.net/figure/Circuit-diagram-of-MOSFET-based-oscillatory-circuit_fig3_332332621

Bertus

Confusing drawing of the schematic! Which is cross over, which is a joint - only a good electronics hobbyist can figure out.

 

[73's de Edd]

Confusing drawing of the schematic!

WHUT you talkin' 'bouts . . . . . . Willis ?

Don't you wowwy never fear, Wobin Hood will soon be here ! . . .Ta Daaaaaaaaaaaaaaaaaaaaaaaaaaa

Little John . . . . . . . . and Elmer Pee Fudd


BEHOLD !


[mod edit: replaced the faulty image with one having the required dots upon request by 73's de Edd]

The 12K Resistor and 2.2 ufd cap sets, RC time constants, set the operating frequency.
Less capacitance or more resistance skews the frequency higher or the converse, if any modification is required with the circuit.

Thaaaaaaaaaaaaaaaaasit . . . . . .

73's de Edd . . . . .

Diplomacy is the art of saying "nice doggy" until you can furtively find a LARGE rock or stick, and work your ways toward it.

 

[ramussons]

You did a great job!!!
Now the Gates of both the FET's are floating............
And there is no power supply.......

 

[73's de Edd]

You did a great job!!!

Praise . . .or cynical fault finding ?
The marked in power supply input is to the far left, recopied as that 1 cell 12V battery.
And I'll just bet that the the inherent cross leakage resistance of those 2 E-caps are alternatively providing sufficient gate damping / pull down via the alternate conducting B-E junctions of the 2222's.
And this is one hell of a nice, simple circuit by virtue of the isolation of the discrete 2222 pair independent oscillator and the CROWBAR like conduction capabilities of those power FET's . ( I would have used a lower Rds unit like an IRF1404 )
Unlike, some circuits that I have seen that are just trying to use two power transistors as a power oscillator.

 

[Harald Kapp]

Aren't we missing a pair of connecting dots?

This is then the classic astable multivibrator (not 'mono stable' as requested by the op as a mono stable circuit will not oscillate) with a pair of MOSFEts for driving the transformer.

 

[73's de Edd]

. . . . . . OOPSIES . . . . . ..indeed . . . . I had put in the forest of trees (dots) and then was experimenting to seeing how much of a white space / gap between lines to leave for a non connection and I then put one in the left drain path up to the transformer line and then neglected to "dot" in those two lower junctions / connections.
Thaaaaaaaasit . . . . .

 

[73's de Edd]

WHUT you talkin' 'bout, Willis ?. . . . .

On the illustration of post #8 there is a back in time holdover example . . . . . of ye olden tymes, in the 1920-30-40's where . . . . . a NON connection of passing / crossing wires is using a half circle inserted in the wire run to designate a non connection of the two crossing wires.
Note it being used, in the central cross over of the E-caps wiring.
Then additionally, in step with modern times, there is the IRF630 Drains upward wiring where a minor cut out of one lead is showing a non connection between that crossover.
Lastly . . . . emboldened black dots show wiring connections being made..

 

[dragon]

I hope no-one attacks me, I cant help but only be as good as I am, But I cant see how that circuit works, to me the transistors wouldn't shut off because the cap would keep leaking through current and keep the base active, and it never shuts off!

<edit> in the astable multivibrator circuit, those caps must be not be discharging, but i can see they have a loop to, it means theres current constantly going through the cap as its coming out, and it would be going to the transistor base!!! </edit>