Author Topic: Wall-wart power supply issue  (Read 1091 times)

koky

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Wall-wart power supply issue
« on: December 29, 2012, 08:34:49 AM »
I have this power supply from an old Panasonic phone. It is 9v -300mA but
These are the readings from DMM when I tested it before I plug it in my newly made effects ::).

And the are the guts


1000 mF Electro - 1
10 nF Film - 2
1n4002 - 4
1. Is there a problem to plug and play  ;D
2. I there is then what can I do to lower the voltage to 9v and to be able to use it safely.

P.S. I am new to electronics and don`t understand lot of things.

Any suggestions are welcome!

Koky
"When you want something in life, you just gotta reach out and grab it." - Christopher McCandless

Pvt. Parts

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Re: Wall-wart power supply issue
« Reply #1 on: December 29, 2012, 09:38:06 AM »
OK lots of things can be happening
1.- the main power supply of your hose is up
2.- MADE IN CHINA
3.- it has an extra 7V for when it is connected to a load
4.- The DMM is only looking at the high pics of the DC wave
5.- all the others combind  ::)

+ you cant use a regular wall-wart (in my experience) the filtering on those things sucks, you get humming product of the bad wave form getting in the signal path, you need nice filtering i.e. a nice flat and steady line of DCV, and 3 caps doesn't make the trick... let me see when i get back to school, Ill grab an oscilloscope and post the different wave forms of a battery, wall wart and a nice voltage regulator  :D

ok you can use it only if you are sure ALL the things you have on the PCB can withstand 20V (I will not be responsible of LED destruction or all the PCB)
"Do what you can with what you have where you are" T. Roosevelt

DutchMF

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Re: Wall-wart power supply issue
« Reply #2 on: December 29, 2012, 09:43:52 AM »
You were a very wise man measuring the output before plugging it in your effects! Some effects can handle higher voltages easy, but others will emit smoke and never function again! You could lower the voltage by using a 9V regulator, but I think you would be better off buying a supply that is built specifically for powering effects. If you decide to make this thing work BE EXTREMELY CAREFULL WITH THE MAINS VOLTAGE INSIDE!!!! That is lethal!!

Paul
"If you can't stand the heat, stay away from the soldering iron!"

koky

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Re: Wall-wart power supply issue
« Reply #3 on: December 29, 2012, 10:06:32 AM »
Thanks for quick answers!
I`ll be fine just to keep using 9v batteries for now  8) and I`ll keep in mind your suggestions especially the one with BIG RED LETTERS;D
I know what it is. When I was 10 - 11 years old I plugged both ends of a wire into the wall socket.  :-X
But I`m still here  ::) ;D ::) ;D
"When you want something in life, you just gotta reach out and grab it." - Christopher McCandless

mandrewbot3k

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Re: Re: Wall-wart power supply issue
« Reply #4 on: December 29, 2012, 10:17:23 AM »
I got a 9v wall wart with my bbe two timer that measures at 12v. I use a godlyke supply though, but you still have to be careful with "effects power supplies"

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Andrew

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madbean

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Re: Wall-wart power supply issue
« Reply #5 on: December 29, 2012, 10:48:04 AM »
9v is the minimum voltage it will supply under a full 300mA load. It's typical of poorly regulated DC supplies to deliver over that. Boss supplies are the same way (the old ones). Mine all measure 12v or more. On the other hand, good supplies should deliver the correct voltage as long as the current draw is within the specification of the supply. For example, the One Spot. I also have a 12v 200mA supply that consistently delivers a rock solid 12v.

Anyway, it really depends on what you are plugging that supply into as to whether or not is could cause damage to an effect. You could easily build up a little regulator vero with a filter cap like a 7809 (which can deliver up to 1A) and a 470uF cap and then power it from that using your existing power supply.
I own madbeanpedals (duh). I am part owner of Function F(X).