Dropping 12vAC down to 9vAC
- LaceSensor
- Cap Cooler
Hi
Anyone know of a simple method to drop AC from 12v down to 9v?
I have a new PSU that outputs 12vAC from one of the slots, but I need 9vAC.
I searched and came up empty. Lots of threads about doubling up
thanks
Anyone know of a simple method to drop AC from 12v down to 9v?
I have a new PSU that outputs 12vAC from one of the slots, but I need 9vAC.
I searched and came up empty. Lots of threads about doubling up
thanks
- DrNomis
- Old Solderhand
Information
- Posts: 6807
- Joined: 16 Jul 2009, 04:56
- my favorite amplifier: Self-Built Valve Amp Head :)
- Completed builds: Dallas Arbiter Fuzz Face,Tone Bender Professional Mk 3,Tone Bender 3-Knob,Baja BK Butler Tube Driver,Baja Real Tube Overdrive,Roger Mayer Octavia,EH Soul Preacher,Tech 21 XXL Distortion,MFOS Weird Sound Generator.
- Location: Darwin,Northern Territory Australia
- Has thanked: 98 times
- Been thanked: 279 times
LaceSensor wrote:Hi
Anyone know of a simple method to drop AC from 12v down to 9v?
I have a new PSU that outputs 12vAC from one of the slots, but I need 9vAC.
I searched and came up empty. Lots of threads about doubling up
thanks
You could try using a suitably rated 5 Watt Wirewound resistor, you only need to drop about 3V if my maths is right, how much current can your power supply put out?...
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- LaceSensor
- Cap Cooler
~The AC power outs are rated 250mA
- DrNomis
- Old Solderhand
Information
- Posts: 6807
- Joined: 16 Jul 2009, 04:56
- my favorite amplifier: Self-Built Valve Amp Head :)
- Completed builds: Dallas Arbiter Fuzz Face,Tone Bender Professional Mk 3,Tone Bender 3-Knob,Baja BK Butler Tube Driver,Baja Real Tube Overdrive,Roger Mayer Octavia,EH Soul Preacher,Tech 21 XXL Distortion,MFOS Weird Sound Generator.
- Location: Darwin,Northern Territory Australia
- Has thanked: 98 times
- Been thanked: 279 times
LaceSensor wrote:~The AC power outs are rated 250mA
Okay, so you could probably use Ohm's Law to calculate what the value of the resistor should be:
E=Volts.
I=Current.
R=Resistance (in Ohms).
P=Power (in Watts).
So, we want to drop 3V across a resistor, current is .25A (250mA), in Ohm's Law R=E/I (Volts divided by Current).
Therefore :
R= 3V/.25A
= 12 Ohms
And 12 Ohm/5 Watt resistors are avalible, 5Watts should be more than adequate....hope that helps....
P=I X V
P = .25A X 3V
= 0.75 Watts
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- Hides-His-Eyes
- Tube Twister
Ah, but the outputs are UP TO 250mA; you need to know the actual DRAW of the pedal.
Testing, testing, won too fwee
- LaceSensor
- Cap Cooler
Hey
Whats the best way to do this? Can a DMM be used?
Thanks
Whats the best way to do this? Can a DMM be used?
Thanks
- DrNomis
- Old Solderhand
Information
- Posts: 6807
- Joined: 16 Jul 2009, 04:56
- my favorite amplifier: Self-Built Valve Amp Head :)
- Completed builds: Dallas Arbiter Fuzz Face,Tone Bender Professional Mk 3,Tone Bender 3-Knob,Baja BK Butler Tube Driver,Baja Real Tube Overdrive,Roger Mayer Octavia,EH Soul Preacher,Tech 21 XXL Distortion,MFOS Weird Sound Generator.
- Location: Darwin,Northern Territory Australia
- Has thanked: 98 times
- Been thanked: 279 times
Hides-His-Eyes wrote:Ah, but the outputs are UP TO 250mA; you need to know the actual DRAW of the pedal.
Good point Hides-His-Eyes....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- Hides-His-Eyes
- Tube Twister
yes! connect up the power supply using crocodile clips or similar and put your multimeter on "AC amps" setting somewhere in series along the power supply (e.g. between the battery and the circuit). Just make sure it's in SERIES.LaceSensor wrote:Hey
Whats the best way to do this? Can a DMM be used?
Thanks
That should give you the current draw, roughly.
Testing, testing, won too fwee