Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: chocopower on June 03, 2014, 01:17:36 pm

Title: Voltage divider for 12vac
Post by: chocopower on June 03, 2014, 01:17:36 pm
Hi!


I need a variable AC voltage from 6vac  to 12vac.


Using a 230v / 12v transformer with a pot wired as voltage divider should work (correct if im wrong).


The problem is that i donīt understand the way it should be wired.


I draw the options i have.



Title: Re: Voltage divider for 12vac
Post by: sluckey on June 03, 2014, 03:22:44 pm
Option B is the correct way to wire it. The voltage out can be varied between zero and 12V.
Title: Re: Voltage divider for 12vac
Post by: chocopower on June 03, 2014, 04:28:40 pm
Quote from: drgonzonm on June 03, 2014, 02:11:43 pm
What kind of amps are you looking at ? 

Is the resistive? like incandesant lamps or inductive like a motor?

A small variac might suite the bill you.


is for that!!


https://www.youtube.com/watch?v=OQxzlv9Iv-Y (https://www.youtube.com/watch?v=OQxzlv9Iv-Y)
Title: Re: Voltage divider for 12vac
Post by: chocopower on June 04, 2014, 10:03:47 am
Quote from: drgonzonm on June 04, 2014, 09:25:18 am
IMO, you do not need variable AC,  why throwaway valuable power in a resistor.....
..............
Would the results be different with a D/C source? probably. 

This thread is a nice change


Ok. But fixed or variable, the voltage divider should be wired as B option. Isnīt?


The guy in the video say that with DC you get different effects.




I think is a nice and simple way to mark our designs!
Title: Re: Voltage divider for 12vac
Post by: chocopower on June 04, 2014, 10:12:13 am
One in english.

http://www.youtube.com/watch?v=U0wTNdgL2Uc#ws  (http://www.youtube.com/watch?v=U0wTNdgL2Uc#ws)

{EDIT: re-did failed YouTube link -- PRR}
Title: Re: Voltage divider for 12vac
Post by: PRR on June 04, 2014, 01:39:42 pm
You do NOT want a Voltage Divider; that is for low-current loads.

As said, for eating metal you want lots of current. You do not need lots of voltage, and the voltage is not very critical.

I've only seen this done with _DC_. DC the correct way will remove metal. AC would seem to take it off then put it on alternately. That may give "an effect" of chewed-up metal, but DC etching is more widely used.

Use a car battery charger. Try and find one with a 6V/12V switch. Start with 6V. If that is very slow, check your electrolyte (often salt, baking soda, or vinegar). If still slow, try the 12V setting.

The second (English) video is using a DC battery charger.
Title: Re: Voltage divider for 12vac
Post by: PRR on June 04, 2014, 02:02:49 pm
http://www.diystompboxes.com/smfforum/index.php?topic=107422.0 (http://www.diystompboxes.com/smfforum/index.php?topic=107422.0)