Transformer

So, I was going through my junk drawer and found a 16 VDC and 32VDC transformer that share a negative. I want to get a good operating voltage on it, but can -32V ruin/overpower an alarm? Ex. Integrity, Genesis, Wheelock AS, and any other alarm really. And is there a way to bring it down to 24VDC or 27?

Yes, you shouldn’t power the alarm with anything more than the specified voltage range.

So is there a way to bring it down? I know another transformer won’t work because it needs AC to drop down.

No,there is no way to bring the voltage down or up.

Correct me if I’m wrong, but can’t you use resistors to lower voltage? (Like EOL resistors do)

No, resisters lower voltages a short amount like .something voltes

Yes, there is. You would need a 2nd transformer to step the main voltage down whatever you need. But that would defeat the purpose of the 1st transformer as you can just buy 1 that goes from 120VAC to X volts DC or whatever else you need.

You guys are very misinformed.

There are ways to lower the voltage:

  1. Use enough resistors, or a large bank of resistors. The problem here though is you need to be aware of the wattage being drawn through it in order to now burn up the resistors. For this reason, that method is not recommended.

  2. Use a voltage regulator. In commercial fire alarm panels, they use a transformer with a voltage output that is much higher than 24 – often 30 or 36 – then they use a rectifier, smoothing capacitor, and voltage regulator to change it to 24 VDC. This would be the best option for you, if you wanted to have a 24 VDC power source from your 32 V transformer, then this would be how you’d do it.

BTW, is this a power brick that was intended for an HP inkjet printer? Sounds like it…

Now about what people suggested:
If you wanted to start with 120 VAC, change it to 32, then use another transformer to reduce it to 24, you would need to find a near impossible to find transformer. Since it would be near impossible, you would end up having to wind your own, which is not an easy task.

Also, the OP specified that his power source is 32 VDC. To DC, a transformer is essentially an electromagnet. It won’t change the voltage at all. With AC current, it generates an electromagnetic field between the coils, and that is how the voltage changes. If you were insane and really wanted to do this, you would then need a power inverter to change the DC back to AC, feed it into the transformer, then use a circuit on the other side to change the AC to DC.

But he does not have a second transformer. And if he did why would he need the first one?

Why don’t you read my post? I explained what the issue with two transformers is…

Why not just buy a proper 24VDC transformer? They’re like $25.

http://www.securitystoreusa.com/IEI-IE-PIP24VDC-PIP-24VDC-Plug-In-Power-Supply-p/479133.htm

Options:

  1. Buy a 24VDC transformer
  2. Use Enough Resistors to lower the voltage.

You didn’t read my post either – I just said that using resistors would be highly impractical.

People do not understand exactly how useful voltage regulators are… $.63 a pop at Mouser. It can take up to 32 volts on the input, and is capable of providing 1.5A, 24vdc. Using resistors, one would need 36, 27 ohm 1 watt resistors. Highly impractical.