Difference between pulsed transformer and electronic ballast

Papabravo

Joined Feb 24, 2006
17,245
Pulse transformers are optimized for rectangular pulses of constant amplitude with fast rise and fall times.

By contrast a "ballast" has high leakage inductance and relatively weak coupling between primary and secondary. Trying to put a rectangular pulse through one would be an exercise in futility.
 

Thread Starter

Chetan_Jadhav

Joined Mar 2, 2017
52
Pulse transformers are optimized for rectangular pulses of constant amplitude with fast rise and fall times.

By contrast a "ballast" has high leakage inductance and relatively weak coupling between primary and secondary. Trying to put a rectangular pulse through one would be an exercise in futility.
thanks,
I have seen a pulsed transformer in UJT triggering oscillator, is it possible to use ballast there?
 

Papabravo

Joined Feb 24, 2006
17,245
I don't think so. Show us the schematic of the UJT triggering oscillator. Why do you want to use a ballast in this application? If you say cost, then I'd bet we can find you a more attractive alternative.
 

Thread Starter

Chetan_Jadhav

Joined Mar 2, 2017
52
I don't think so. Show us the schematic of the UJT triggering oscillator. Why do you want to use a ballast in this application? If you say cost, then I'd bet we can find you a more attractive alternative.
here is the circuit

UJT-firing-circuit.jpg
 
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bertus

Joined Apr 5, 2008
21,667
Hello,

Where did you get the schematic?
The circuit will likely not work.
The zener diode is the wrong way around.
At the moment there will be only 0.7 Volts on the zener.

BTW, where does the AC voltage for the load come from?

Bertus
 

MaxHeadRoom

Joined Jul 18, 2013
23,908
With a UJT pulse transformer you want pulse transfer as fast as possible, this is one reason why they usually have a ferrite core.
A typical 'Ballast' transformer is generally a large iron core device and construction is usually intended for the opposite effect, even the electronic type would have a problem I would think.
I have purchased any pulse transformers I needed from Hammond.
Max.
 

Papabravo

Joined Feb 24, 2006
17,245
I see what allows the SCR to be triggered, but I'm less clear about how the AC current drops to 0 so the SCR can be turned off. Never mind that for the moment, I'm reasonably confident that a ballast would be unlikely to produce anything like the waveform you would need. If you want to try the experiment, by all means tell us what you find; but I'm not holding my breath for a positive reply.
 

LesJones

Joined Jan 8, 2017
3,570
I would have thought that a good item to try would be the mains input filter from a switched mode power supply. (The type that is a ferite toroid with two windings on it. the live passes through one winding and the neutral through the other.) Note the windings must be phased correctly.

Les.
 

Thread Starter

Chetan_Jadhav

Joined Mar 2, 2017
52
Hello,

Where did you get the schematic?
The circuit will likely not work.
The zener diode is the wrong way around.
At the moment there will be only 0.7 Volts on the zener.

BTW, where does the AC voltage for the load come from?

Bertus
thanks for pointed out error in the Zener diode.
AC voltage for the load is from mains(230 V 50HZ) load is incandescent bulb when we change the firing angle of scr intensity of light should change.this is my objective
 

Thread Starter

Chetan_Jadhav

Joined Mar 2, 2017
52
I don't think so. Show us the schematic of the UJT triggering oscillator. Why do you want to use a ballast in this application? If you say cost, then I'd bet we can find you a more attractive alternative.
hi,
you just said about a better attractive alternative. please tell me if you have any
regards.
 

Papabravo

Joined Feb 24, 2006
17,245
hi,
you just said about a better attractive alternative. please tell me if you have any
regards.
See Max's suggestion that you try Hammond
http://www.hammondmfg.com/600.htm
http://www.hammondmfg.com/612.htm
http://www.clrwtr.com/PDF/Hammond/Hammond-Pulse-Transformers.pdf

I have used Pulse Electronics for my needs in this regard.
http://www.pulseelectronics.com/

Unfortunately for us the schematic has no specifications or requirements for the pulse transformer. You're on your own to make sure you select a part that is appropriate for the application. You might start with the specifications for the SCR.
 

ian field

Joined Oct 27, 2012
6,539
hello,
Can anyone tell me the difference between pulsed transformer and electronic ballast.
regards
An electronic ballast usually contains a pulse transformer of some sort or other - its more or less an SMPSU.

That's stretching the definition of "pulse transformer" though. You might perhaps think along the lines of a typical pulse transformer being between the pulse generator and the gate of a SCR or triac. There are millions of applications in digital electronics, especially when you need electrical isolation between two digital subsystems.
 

profbuxton

Joined Feb 21, 2014
419
Seems like a bit of over kill to me. I have made a simple SCR control for small motors etc. just using using suitable trigger circuit driving phase shift into SCR gate. Runs straight off 240 AC. SCR switches off when AC polarity reverses so only get half wave control though.
 

MaxHeadRoom

Joined Jul 18, 2013
23,908
hello,
Can anyone tell me the difference between pulsed transformer and electronic ballast.
I have seen a pulsed transformer in UJT triggering oscillator, is it possible to use ballast there?
regards
Fairchild AN-3006 gives you a triac opto alternatives to the trigger transformer.
Max.
 
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