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Post by night0wl on Mar 19, 2006 16:29:00 GMT -5
Hi all,
I just got hold of a dB wireless mic and the power adaptor that came with it has a foreign plug/pin setup.
It is a 12v 250mA 3VA transformer and I am wondering if I can use a 12v 300 or 500mA transformer safely without damaging the unit?
Thanks, Shane
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servant
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Post by servant on Mar 19, 2006 17:17:37 GMT -5
Shane,
Wait until someone else who is sure answers before you try it, but I think the higher current rating on the PS will be fine. Let's say the wireless unit draws 200mA of current. Your other supplies are rated higher than that so you should be OK.
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nexis
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Post by nexis on Mar 19, 2006 20:10:22 GMT -5
A while back at radio shack looking for a transformer, They said that the milliamps have to match also or there's a risk or damage. I don't know if they were correct or not. Ended up replacing everything because I couldn't find one that matched.
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Post by night0wl on Mar 19, 2006 20:55:50 GMT -5
I talked to the company who supplied the wireless mic today and they supplied a transformer to use with it. The transformer is 12vAC 1.25A .... according to the users manual, the unit uses 12vAC 250mA. Seeing they supplied the transformer I will try it and see if it works OK.
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Post by UnklMickey on Mar 20, 2006 13:36:18 GMT -5
some basic rules of thumb on power adapters: - 1 - same voltage
- current rating of supply = or greater than required.
- VA is voltage x current product.
- AC or DC and polarity:
- don't subsititute AC for DC or vice-versa
- polarity of plug is meaningless for AC supplies
- polarity of plug is critical for DC supplies
Shane, that 1.25A supply should run very cool, since it will only need to supply 1/5 of it's rated power. should work fine. unk
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Post by night0wl on Mar 20, 2006 14:16:39 GMT -5
Thanks unk, I tried it out and everything is fine. Great sounding mic to!
Cheers, Shane
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Post by JohnH on Mar 21, 2006 6:31:26 GMT -5
Shane - looks like you have it all sorted.
I was just going to add that some devices need a regulated supply and some don't, and so that is another feature to check for when selecting a power supply.
John
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Post by UnklMickey on Mar 21, 2006 9:44:27 GMT -5
good point, John.
the applications where an external supply is regulated, are much less common. but if an unregulated supply is substituted in these apps, performance will suffer badly.
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Post by night0wl on Mar 21, 2006 15:37:49 GMT -5
Cool John, is there any info I can read about this? I have a tendency to just get the closest transformer I can find when one stops working. Infact until now I only checked for the voltage and mA readings, ignoring DC/AC and polarity! Thanks Shane P.S. hope you don't mind but I am copying and pasting this info into a text document so I can refer to it quicker than searching for the post online.
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Post by JohnH on Mar 22, 2006 3:05:54 GMT -5
Shane - Im not sure where to read about it. I know D!ck Smith and Jaycar sells both stabilsed and unstabilised types. I recently had to replace one for a digital TV box, which needed to be stabilised. Ive also bought unstabilised ones for powered speakers that hummed badly until I added some hefty caps to smooth them.
Id be interested to know what type of supply is normally recommended by manufacturers of effects pedals?
John
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Post by dumenegozzo on Mar 30, 2006 23:06:44 GMT -5
Folks, just wanted to add that when you get a transformer that big for so little current draw, you're carrying a lot of weight for nothing. It's always good to have "spare" current, but five times the need seems a little too heavy for me.
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