electrical question

mufc802 · 8 Jan 2011 at 19:06

I've bought a radio kit which requires a 12v/100mA power supply but it didn't come with one. I was wondering if my laptop charger would work or not, it says it's 19v/4.74A output on it.

geuben · 8 Jan 2011 at 19:07

no, it will damage it.

Emphacy · 8 Jan 2011 at 19:10

The voltage is too high, it will blow the circuit.
If you can find something with the same voltage (V) then it will be fine.
Amount of current in Amperes (A) doesn't particularly matter, the circuit draws as much current as it needs.

mufc802 · 8 Jan 2011 at 20:04

Great, I found a 12v supply that is for my router, will that be ok? It's 1.5A.

fidget · 8 Jan 2011 at 20:07

Yateszy said:
Great, I found a 12v supply that is for my router, will that be ok? It's 1.5A.

Should be. Check it's an DC adaptor and not AC and that you get the polarity right.

mufc802 · 8 Jan 2011 at 20:09

fidget said:
Should be. Check it's an DC adaptor and not AC and that you get the polarity right.

It's AC, does that mean it wont work? It does seem to plug into the radios power input fine.

Emphacy · 8 Jan 2011 at 20:47

Does the radio require a DC input?
It should say near the connector, in the instructions or on a label on the bottom of the radio next to the input specs.

The router adapter or any adapter for that matter which you may consider using must have the same kind of output as the input for the radio. You need a DC adapter for a DC radio and AC for AC.

Polarity is given by a small +/- or a -/+ on both the adapter and radio, make sure that these are the same.

Steve2000 · 8 Jan 2011 at 20:52

Make sure the router supply is DC, if that's what the radio needs.

Also check the polarity. If it is centre negative and you put a centre positive adaptor into it you could damage it.

mufc802 · 8 Jan 2011 at 21:16

Steve2000 said:
Make sure the router supply is DC, if that's what the radio needs.

Also check the polarity. If it is centre negative and you put a centre positive adaptor into it you could damage it.

I don't really understand the bit about polarity.. it can only go in one way. How do I know if it's ok?

Murray · 8 Jan 2011 at 21:18

Try it if nothing blows up or goes on fire you are fine.

Dfhaii · 8 Jan 2011 at 21:28

Yateszy said:
I don't really understand the bit about polarity.. it can only go in one way. How do I know if it's ok?

There will usually be a symbol with a couple of concentric circles, with lines coming from them to show if the which of the outside edge or inside edge of the connector is positive and which is negative, you need to make sure this is the same as the power connector on your radio kit.

If it is AC though then you're pretty much out of luck without rectifying and smoothing before putting it into your radio, at that point it's probably easier to find another adaptor!

mufc802 · 8 Jan 2011 at 21:31

It's an AC adaptor, but not sure if that means AC to 12v DC or not.

Dfhaii · 8 Jan 2011 at 21:32

Is there a symbol with a flat line and a dashed line above it on the power supply anywhere?

What does it say on the back actually, or post a photo

Jokester · 8 Jan 2011 at 21:34

I would be amazed if the router power supply output 12V AC.

mufc802 · 8 Jan 2011 at 21:36

Dfhaii said:
Is there a symbol with a flat line and a dashed line above it on the power supply anywhere?

What does it say on the back actually, or post a photo

http://cgi.ebay.co.uk/AC-Adaptor-AA-121A5D-OEM-12v-Power-Adaptor-New-/300487763085

Dfhaii · 8 Jan 2011 at 21:42

That does indeed look like 12V AC output

Emphacy · 8 Jan 2011 at 22:06

Jokester said:
I would be amazed if the router power supply output 12V AC.

My router uses a 12V AC Input.

Also most adapters now are standard polarity, negative on the outside, positive on the inside.

Like has already been said, just try it anyways, most modern electronics now also have diodes to stop any current going in the wrong way, so it's likely it would just not work rather than 'blow up'.

You need to look on the Output section on the adapter. Whatever the output type is on the adapter MUST be the same as the input type on the radio

Input on any adapter will always be 230/240V AC. Therefore this doesn't make any difference.

Steve2000 · 8 Jan 2011 at 22:30

Yateszy said:
http://cgi.ebay.co.uk/AC-Adaptor-AA-121A5D-OEM-12v-Power-Adaptor-New-/300487763085

That outputs AC. If that's the plug you have and your radio needs a DC input, then that will probably fry it.

mufc802 · 8 Jan 2011 at 22:46

Steve2000 said:
That outputs AC. If that's the plug you have and your radio needs a DC input, then that will probably fry it.

Can I ask how do you know if the output is AC or DC?

Steve2000 · 8 Jan 2011 at 22:51

If you look closely where it says Output 12v ~ 1.5A, the little ~ symbol means AC, if it was DC it would be a line with three short dashes underneath it.