electrojules
New Member
Hi guys...
I am using a very simple two transistor (KSE13009L ,700Vcbo 400Vceo 24A Icp), and two resistor oscillator circuit to provide 24v ac to a coil, the coil is 10 turns 18awg on a ferrite core(theres also a second coil providing feedback to the transistors but that is irrelivant to my question), the circuit has to be powered from a 24v lead acid cell..... no other option is feasable.
I designed this oscillator to use the least components possible and be as simple as physically possible.... it has to stay that way due to the insane rf and flux the bits on the other end of the ferrite core generate! more bits = more interferrence + more popped stuff...
Due to the insanely low "H" of the 10 turn coil it is effectively a dead short on the transistors, hence my problem..... CURRENT LIMITTING!!!
as you know a low ohm (1k8) high watt (10w) resistor still glows red hot delivering 6A,
and I need to limit the supply current to approx 6-20A (pref adjustable),using a resistor is not only hazardous but inefficient.
I have designed an adjustable current limiter based on the 2n3055 npn, it works , but delivers only 4A and still gets really hot.
has anyone got another (preff simple) supply limiting solution to keep the smoke in the transistors?
adjustabillity is prefferable but not essential.
Cheers
(P.S. I was using a more complex circuit using IRF520 mosfets which was self limmiting ....but the RF interference and back EMF surge of the secondary ensures a short lifespan despite protective circuitry! Hence the simple transistor curcuit, cheaper, easyer, and for reasons I cant easily explain, it survives the feedback of the secondary )
I am using a very simple two transistor (KSE13009L ,700Vcbo 400Vceo 24A Icp), and two resistor oscillator circuit to provide 24v ac to a coil, the coil is 10 turns 18awg on a ferrite core(theres also a second coil providing feedback to the transistors but that is irrelivant to my question), the circuit has to be powered from a 24v lead acid cell..... no other option is feasable.
I designed this oscillator to use the least components possible and be as simple as physically possible.... it has to stay that way due to the insane rf and flux the bits on the other end of the ferrite core generate! more bits = more interferrence + more popped stuff...
Due to the insanely low "H" of the 10 turn coil it is effectively a dead short on the transistors, hence my problem..... CURRENT LIMITTING!!!
as you know a low ohm (1k8) high watt (10w) resistor still glows red hot delivering 6A,
and I need to limit the supply current to approx 6-20A (pref adjustable),using a resistor is not only hazardous but inefficient.
I have designed an adjustable current limiter based on the 2n3055 npn, it works , but delivers only 4A and still gets really hot.
has anyone got another (preff simple) supply limiting solution to keep the smoke in the transistors?
adjustabillity is prefferable but not essential.
Cheers
(P.S. I was using a more complex circuit using IRF520 mosfets which was self limmiting ....but the RF interference and back EMF surge of the secondary ensures a short lifespan despite protective circuitry! Hence the simple transistor curcuit, cheaper, easyer, and for reasons I cant easily explain, it survives the feedback of the secondary )
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