Current control and defence

[CircuitMaster]

Good day! I am trying to make a current limiting part for a schematic for charging lead batteries for automobiles. I use this popular schematic on the net, normally I would use a microcontroller to control the thyristor but I have here one transistor in order to limit the current through the acumulator. The idea is to use the potentiometer RV1 to limit the current through the Transistor base. Do you think it will work? Do I need to put resistors in the collector and emitter?

 

[BobK]

Without a schematic, the best I can say is maybe.

Bob

 

[CircuitMaster]

I am certain I uploaded it but no matter! Later I will upload another one that I made by myself..




[mod edited to place image into the thread]

 

[(*steve*)]

Presumably the TIP142 is there to act as a smoke generator?

From the look of this circuit it shorts out the battery.

 

[cjdelphi]

Popular circuit?

Why a thyristor is my question, is this not an ac circuit, so why use one

Question, 9v out?

 

[cjdelphi]

That is a dodgy circuit lol

 

[(*steve*)]

The input may be pulsed DC. SCRs have been used as regulating elements. Given what seems to be a major design fault whether I'm not going to try to figure out what's up with this part of the circuit.

 

[CircuitMaster]

Everything else except the transistor works perfect. Yes the transistor short circuits the battery so it may reduce the current. The input is AC but since we have a thyristor and the diodes, at the kathode of the thyristor we have DC voltage. According to proteus it works, but still I am not so certain. The only problem is the current regulation because too high current can damage the battery. The battery was suppose to be 12V, that is my mistake I am sorry for that!

 

[(*steve*)]

Why do you want to short the battery? All that will do is discharge the battery.

 

[CircuitMaster]

It should not discharge it as long is there is charging current from the thyristor, the idea is that the transistor should take away part of the current and thus regulate it as long is there is something to power the transistor base, like I said I do not know if it will work, maybe I should put resistors in the collector and emitter but the whole idea was to avoid the resistors because they will be with a high wattage. If you have any other idea to regulate the current through the acumulator please tell me? Thank you in advance!

 

[(*steve*)]

What you are saying is wrong in too many ways to easily set you straight.

What sort of battery is it? Is it a lead acid battery? If so, what capacity? SLA?

What power source do you have?

 

[CircuitMaster]

It's a lead acid battery, the rest I do not know. It will be charged with 2A, 14.4V. There is a transformator coil connected to the thyristor anode.

 

[(*steve*)]

Where does that circuit come from? As far as I can tell it's badly wrong, but if you can point me to a source I may be able to make more sense of it.

 

[Alec_t]

Diverting current through the transistor will place a heavier load on the AC supply. Unless the supply itself has some way of limiting current (e.g. significant resistance) it may self-destruct.

 

[Harald Kapp]

The input is AC

The symbol at the input indictaes DC which is really bad as the thyristor, once triggered, will stay on until the current falls below the hold currrent. However, Q1 will ensure that current flows even when the battery is charged.
As Steve asked in post #13 we need to know where this diagram comes from.

I use this popular schematic on the net

It doesn't seem to be that popular. A quick search turns up heaps of other schematic diagrams, but not this one.