Looking for Voltage switch TO-220 400v 5v

[hfireworks]

I am looking for a voltage switch that will handle 400vdc and be switched by 5vdc.

Transister, Darlington Pair, SCR, just looking for the best option at the lowest price per piece to handle that amount of voltage for computer switching.

Would prefer to stay in the TO-220 chip with the E C B.

Any suggestions?

 

[Hero999]

I'm not meaning to be rude but what is the point of this?

What exactly are you trying to do?

This isn't one of the things that you would normally do in isolation; it is typically part of a larger project. It is easier for us to provide help if we can see the bigger picture.

 

[hfireworks]

I'm not meaning to be rude but what is the point of this?

What exactly are you trying to do?

This isn't one of the things that you would normally do in isolation; it is typically part of a larger project. It is easier for us to provide help if we can see the bigger picture.

The project is computer firing systems, I have been building electronic firing systems for display fireworks. This is the 2nd system I have designed for display fireworks. The system I am working on now is computer gererated and produces a voltage of 5vdc to trigger the supply. I am looking for a TO-220 silicon switch that would be triggered by this low voltage and switch the high power of the 200vdc capacitive discharge system I have in my systems.

There are several available from SCR's to transistor's and I am looking for your recomendations for this application.

 

[Hero999]

You still haven't provided enough information.

What current do you require and how long does the pulse last for?

Do you require isolation between the high and low voltage side?

If so then you need to use an optocoupler or a pulse transformer (this can be made pretty cheaply from a ferrite bead).

 

[hfireworks]

You still haven't provided enough information.

What current do you require and how long does the pulse last for?

Do you require isolation between the high and low voltage side?

If so then you need to use an optocoupler or a pulse transformer (this can be made pretty cheaply from a ferrite bead).

The power souce produces 175ma to the 100uF capacitors and I do not need isolation

 

[Hero999]

But what current flows when the capacitors are discharged?

1A, 100A, 1kA?

 

[hfireworks]

But what current flows when the capacitors are discharged?

1A, 100A, 1kA?

That I do not know. I am using a 200vdc 175ma power souce with 100uF capacitors.

 

[Hero999]

You can calculate the peak current by measuring the resistane of the squibs you're using with Ohm's law.

 

[hfireworks]

You can calculate the peak current by measuring the resistane of the squibs you're using with Ohm's law.

300' of cable is 600' out and back.
600 * 0.02567 = 15.402 ohms

ematch are about 2 ohms
amp = volts / ohms

The problem is calculating the current when it comes to a 100uF capacitor.

 

[Hero999]

That works out at 9.2kA to begin with which will decay to 63% of the origional value in C×R which is 1.74ms. In practice, there will be some inducatance which will reduce the peak current and increase the fall time but the energy will still be the same.

https://en.wikipedia.org/wiki/CR_circuit

I don't know if a typical SCR is up to the job, at least not a typical TO-220 unit anyway. You need something like a thyratron to do this proply.

 

[hfireworks]

That works out at 9.2kA to begin with which will decay to 63% of the origional value in C×R which is 1.74ms. In practice, there will be some inducatance which will reduce the peak current and increase the fall time but the energy will still be the same.

https://en.wikipedia.org/wiki/CR_circuit

I don't know if a typical SCR is up to the job, at least not a typical TO-220 unit anyway. You need something like a thyratron to do this proply.

thyratron seems to be overkill in this situation? I am looking at different switchs. We are talking switching 200vdc capacitive voltage with low 5vdc.

 

[eblc1388]

That works out at 9.2kA to begin with which will decay to 63% of the origional value in C×R which is 1.74ms.

9.2kA, that's 9200A!!! Care to show your calculation.

The connection cable alone has resistance of 15.2 ohm. At 200V, that's a little more than 13A, using ohm's law.

 

[Hero999]

Lol, you're right.

I did the calculation for instantaneous power instead.

The maximum voltage he's intending to use is 400V which will give 26A

A normal SCR will do providing it can handle the peak current, try the 2N6397.

 

[hfireworks]

Lol, you're right.

I did the calculation for instantaneous power instead.

The maximum voltage he's intending to use is 400V which will give 26A

A normal SCR will do providing it can handle the peak current, try the 2N6397.

I have located a Triac NTE5608 it will handle 400v which is over my needs and 8amp, it has a gate of 2.5v which I can use a resister to drop the voltage from the 5v.

I have looked at the SCR's in most the SCR will open the voltage from the gate and remain open, The Triac will open and close as soon as the power is dropped. I have this Triac in stock now and will test it.

I would like to here any other ideas also.

 

[Hero999]

TRIACs are just two SCRs connected back-to-back. SCRs will also remain open until the current drops below the holding current which is stated on the datasheet.

If you want to turn the TRIAC off inbetween fireings you could use a comparator that turns the DC-DC converter off when the voltage on the capacitor exceeds a certain set voltage.

 

[hfireworks]

TRIACs are just two SCRs connected back-to-back. SCRs will also remain open until the current drops below the holding current which is stated on the datasheet.

If you want to turn the TRIAC off inbetween fireings you could use a comparator that turns the DC-DC converter off when the voltage on the capacitor exceeds a certain set voltage.

That is interesting, I am going to test both, I ordered the SCR and I have the Triac. I will post my results as soon as I get the test done.

Your thoughts are always welcome.

 

[hfireworks]

I am still looking at options on a switch, the Triac and the SCR both require a secondary disengage switch to deactivate them.
I really need a switch that opens when the gate is activated and closes when the gate is deactivated from the same switch almost right away. Or I need a diagram of a circuit that will disegage the Triac or SCR in that manner using other componets.

 

[Hero999]

You could try a power MOSFET but can't you just disable the inverter after the SCR has been fired?

 

[hfireworks]

You could try a power MOSFET but can't you just disable the inverter after the SCR has been fired?

Trying to keep the amount of circuitry down to a min is going to be hard. I am looking at almost 170 switchs to do the job. The case is about 14" x 9" x 4" and will house 2-12volt batteries plus the circuit board for my high voltage converter.

There is never an easy way around it.

 

[mneary]

Isn't the squib destroyed when you fire it? This would turn the SCR off.