Dropping 26v ac to stable 24v ac

Thread Starter

s200bym

Joined Aug 9, 2017
82
Hi guys,

I have a centre tap transformer it’s supposed to be 25v but I’m getting 26v-0v-26v.

Is there a way I can drop the voltage and get one side of the transformer to power a single 24v ac circuit?

Kind Regards
Mike.
 

Alec_t

Joined Sep 17, 2013
14,280
If there's space you could add a few turns to the transformer and connect them in series with the secondary to buck the voltage down ~2V.
 

philba

Joined Aug 17, 2017
959
Is the 24vac circuit/device that critical?
Max.
this!

To expand, most components have a tolerance - some variation due to manufacturing differences is expected. I'd be surprised if your circuit couldn't handle 8% difference.

Transformers will exhibit voltage drop as the load goes up. Wall warts are spec'd for X Volts at Y Amps but when you measure the voltage without a load, it's always higher. Load it down so the current is at Y Amps and the voltage will measure within some tolerance of X (and within the tolerance of your DMM).

Also, if you are measuring the voltage with the transformer plugged into 120VAC (or 240VAC), be aware that the mains voltage also varies a fair amount. It too, has a tolerance.

And finally, your DMM probably also has some error unless it's been calibrated.. Again, tolerance. And calibration doesn't mean precise, just that it's within some tolerance.

If you absolutely, positively must have exactly 24VAC, get a variac and use it to tune the input voltage. Also, get a calibrated DMM so you can measure with reasonable precision. However, I seriously doubt you need that much precision.
 
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