Need a current limiter design.

[northendtrooper]

I have way too much current going back to my DC power supply (6v/6a). I have a 4 ohm heating element that I need to keep up at max current. What could be used, minimally in parts, to bring down the amps to keep from killing/cooking my DC supply.
Cheers,
trooper

 

[ericgibbs]

hi,

A 4 Ohm resistor connected to a 6V supply will only draw 6V/4R = 1.5 Amps.

Is this what you are asking.??

E.

 

[northendtrooper]

Eric,
I just got back from doing some quick measurements. Excuse me that the resistance that I am looking at for my nichrome coil is .1-.4 ohms, yes it is very small. I have a stack of AA Duracell Copper Top batteries in series putting down 6v and 9amps. Each Copper top has the ability of 2+amps.
I need a circuit that will allow the nichrome to heat up to 800 degree (I did the math for this gauge and amps) and have a following circuit/chip to down the volts/amps back to the battery so it doesn't heat them up. Basically too much current/voltage back to the batteries. I am researching transformers, inverting amp, capacitors and inductors for my solution. I can't do much resistance because the low impedance of the nichrome.

 

[crutschow]

You need an efficient way to convert the battery voltage to the low voltage and high current required by the nichrome wire. Typically that would be done with a switching regulator.

 

[alec_t]

I have a stack of AA Duracell Copper Top batteries in series putting down 6v and 9amps. Each Copper top has the ability of 2+amps.

If the batteries are in series and each can produce ~2A then the series stack can produce ~2A, not 9A.
AA cells will generate 2A for a short time only (<30 mins).

 

[northendtrooper]

crutshow, if you could please show me an example of the circuit you are referring to. Please be patient with me, I haven't been in electronics for over 5 years so I feel like I'm new to the game all over again.

alec, I recommend putting 4 AA in series and tell me what the amps are. You would be surprised as much as I was.

 

[alec_t]

I recommend putting 4 AA in series and tell me what the amps are.

No thanks: I can't afford to flatten AA cells like that. Supplying AAs for my grandchildren's various gadgets is costly enough

 

[audioguru]

Four AA alkaline cells in series produce 6V only when they are brand new.
With a 4 ohm load (1.5A!) then their voltage quickly drops and the current also drops.

Duracell have a graph for their AA alkaline cell that shows its voltage dropping very quickly with a 0.5A load. It is not suitable to use a 1.5A load.

 

[MikeMl]

Hey trooper, do you have **broken link removed**? If so, take off the tip and hook it to your Nichrome wire.

 

[crutschow]

crutshow, if you could please show me an example of the circuit you are referring to. ......................................

Something like this.

 

[ronv]

It seems like you would be better off if you used a single battery and chose your wire size to match it. This sounds like a lighter? Give a few more details like wire length and gage and what it is used for.

 

[audioguru]

I think it is an electric cigarette that produces a vapour. They use a little rechargeable battery.