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DIY Stompboxes => Building your own stompbox => Topic started by: Bernardduur on October 21, 2005, 11:20:15 AM

Title: Easiest way to get +9V from a +18V supply
Post by: Bernardduur on October 21, 2005, 11:20:15 AM
Ok. What is the easiest way to do this. I have now two pedals into one housing (Fulldrive II and a Hot-tubes) and as I LOVE the Fulldrive on 18V, I dislike the Hottubes on this.

I already tried a normal Vref downgrade of +18V but that did not work.

Someone?
Title: Re: Easiest way to get +9V from a +18V supply
Post by: cd on October 21, 2005, 11:22:43 AM
7809 regulator.
Title: Re: Easiest way to get +9V from a +18V supply
Post by: Bernardduur on October 21, 2005, 11:29:26 AM
Wow..... is it that simple?

Just put 18V in the device, out comes 9V......

Wow.
Title: Re: Easiest way to get +9V from a +18V supply
Post by: A.S.P. on October 21, 2005, 01:13:16 PM
information lost...
Title: Re: Easiest way to get +9V from a +18V supply
Post by: transient on October 21, 2005, 03:27:24 PM
Not totally sure, but i guess a 9V zener diode could also do the job.

.
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Title: Re: Easiest way to get +9V from a +18V supply
Post by: Aurin on October 21, 2005, 03:30:12 PM
Wouldn't the 9V zener diode just start allowing flow @ 9V (As in nothing until you hit 9V then everything after that -- until it burns out of course) ?
Title: Re: Easiest way to get +9V from a +18V supply
Post by: ocelot on October 21, 2005, 04:22:46 PM
a 7809 regulator is the best way to go add a capacitor to the input say a 100uF

Cheers
Title: Re: Easiest way to get +9V from a +18V supply
Post by: transient on October 21, 2005, 04:48:23 PM
Quote from: Aurin on October 21, 2005, 03:30:12 PM
Wouldn't the 9V zener diode just start allowing flow @ 9V (As in nothing until you hit 9V then everything after that -- until it burns out of course) ?

I remember reading about using zener diodes to drop voltage. I think the zener's supposed to be placed from ground to +18, this way it will limit the voltage to 9V. You also need a resistor before the zener, to limit the current through the zener(as in LEDs).

However this might not be the best approach as you need to lose 9 volts, a zener might not be able to handle that much dissipation.

.
e
Title: Re: Easiest way to get +9V from a +18V supply
Post by: Aurin on October 21, 2005, 05:13:13 PM
Hrm.... Point... wasn't thinking of it that way --- Like using LEDs to drop 1.6V at a time....  Ah, the follies of being a home-schooled newbie =)
Title: Re: Easiest way to get +9V from a +18V supply
Post by: transient on October 21, 2005, 06:20:37 PM
Here's a nice zener link:
http://www.allaboutcircuits.com/vol_3/chpt_3/9.html

.
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