The cold current calculation (with V = I * R) will be higher than the
running current, and this failure occurs after it's been running for a
while. The P = E * I is a better indicator of what you are working with.
John T. Blair wrote:
>
> Next you'll want to disconnect the wires from the xformer and using the Ohms
> setting of your multi meter measure the resistance between the 2 wires.
> This will tell you what the cold resistance of the wire & 2 bulbs is.
>
> >From that you can calculate about how much power you need to supply.
>
> V = I * R , You'll now V = 24, the Resistance of the bulbs is R, so
> I = V/R. Now you know the current that you'll require. Then I'd go
> with a safety factor of 2 or 2 times as much current as the calculations
> say.
>
> The other possibility is, are the bulbs marked as to how many watts they
> are? If so, then Power = V * I. So if we assume the bulbs are 20w each,
> you are using 40W of power. So I = P/V, or 40/24V is approximately 2 amps
> of current. Again, double the 2 amps and find a 24V xformer that will handle
> 4 amps.
>
> I think you'll find that your bell xformer is rated at either 250 or 500 ma
> or 1/4 to 1/2 amp max. So you are trying to get it to output at least 4X
> what it can handle.
>
> John
>
>
> John T. Blair WA4OHZ email: jblair1948@cox.net
> Va. Beach, Va
> Phone: (757) 495-8229
>
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