13 Volts AC in a car?

mackinthebox · 11th May 2011, 08:16 AM

How can convert 12VDC to 13VAC?
Im integrating an amplifier into my dash and pretty much sealing the whole thing up so it cant be stolen
all you will see will be a volume knob, a couple RCA jacks (i may even hide those...) and maybe some VU meters if I can figure out this AC power thing...

ive got a VU driver board but it requires 13VAC
I thought about just installing a small inverter for 110vac and plugging the power supply into that but that would take up alot of room and just doesnt seem clean enough

anyone have any ideas?

Perry Babin · 11th May 2011, 08:21 AM

Do you have a schematic diagram for the board?

mackinthebox · 11th May 2011, 08:23 AM

i dont think so, i got it off of fleabay, let me see what I can dig up...

mackinthebox · 11th May 2011, 08:24 AM

no schematic but there are some very close up shots of the board

posting as links as the pics are pretty big

http://i121.photobucket.com/albums/o...2/4e6d2283.jpg
http://i121.photobucket.com/albums/o...2/8d1b1226.jpg
http://i121.photobucket.com/albums/o...2/458528f3.jpg

mackinthebox · 11th May 2011, 08:25 AM

and apparently its 18vac and not 13...

sofaspud · 11th May 2011, 08:34 AM

AC18~24V according to the board.
What is the black component between the 2 green terminal blocks in the first picture? Can you give us a part number?
I'm thinking this thing has onboard rectification to DC. I'd bet the rent on it.
Is that a TO220 LM7812? If so, you can just tap in there with your car's DC.

mackinthebox · 11th May 2011, 08:38 AM

unfortunately i dont have the board with me, I will post some details on the black box when i get home from work in a couple hours

sofaspud · 11th May 2011, 08:41 AM

OK. The good news is you don't need a voltage inverter. The bad news is you have to find where you can tap into the circuit and also verify you have a calibrated unit after you make the mod. Nothing to fret about though.

Perry Babin · 11th May 2011, 08:51 AM

If the AC is rectified into a single positive rail, you may be able to feed it DC. 18v of AC will give you about 25v of DC (which is what you'd want from what's shown on the datasheet for the IC). You could get 25v DC from rectifying the AC on the primary of one of the amp's power supplies.

If the power supply needs to be isolated from ground. You could get the power from the same source but you'd have to run it through a small transformer (which you could wind yourself).

It's likely to be a single-ended supply since there aren't two identical rail capacitors.

WSJ · 11th May 2011, 10:07 PM

The TA7318P data sheet has a circuit with a single +25 V supply.

Toshiba TA7318P data sheet

11th May 2011, 08:16 AM	#1
mackinthebox diyAudio Member Join Date: Oct 2010	13 Volts AC in a car? How can convert 12VDC to 13VAC? Im integrating an amplifier into my dash and pretty much sealing the whole thing up so it cant be stolen all you will see will be a volume knob, a couple RCA jacks (i may even hide those...) and maybe some VU meters if I can figure out this AC power thing... ive got a VU driver board but it requires 13VAC I thought about just installing a small inverter for 110vac and plugging the power supply into that but that would take up alot of room and just doesnt seem clean enough anyone have any ideas?

11th May 2011, 08:21 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have a schematic diagram for the board? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

11th May 2011, 08:34 AM	#6
sofaspud diyAudio Member Join Date: Nov 2005 Location: San Antonio TX	AC18~24V according to the board. What is the black component between the 2 green terminal blocks in the first picture? Can you give us a part number? I'm thinking this thing has onboard rectification to DC. I'd bet the rent on it. Is that a TO220 LM7812? If so, you can just tap in there with your car's DC. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

11th May 2011, 08:41 AM	#8
sofaspud diyAudio Member Join Date: Nov 2005 Location: San Antonio TX	OK. The good news is you don't need a voltage inverter. The bad news is you have to find where you can tap into the circuit and also verify you have a calibrated unit after you make the mod. Nothing to fret about though. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

11th May 2011, 08:51 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the AC is rectified into a single positive rail, you may be able to feed it DC. 18v of AC will give you about 25v of DC (which is what you'd want from what's shown on the datasheet for the IC). You could get 25v DC from rectifying the AC on the primary of one of the amp's power supplies. If the power supply needs to be isolated from ground. You could get the power from the same source but you'd have to run it through a small transformer (which you could wind yourself). It's likely to be a single-ended supply since there aren't two identical rail capacitors. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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11th May 2011, 08:23 AM	#3
mackinthebox diyAudio Member Join Date: Oct 2010	i dont think so, i got it off of fleabay, let me see what I can dig up...

11th May 2011, 08:24 AM	#4
mackinthebox diyAudio Member Join Date: Oct 2010	no schematic but there are some very close up shots of the board posting as links as the pics are pretty big http://i121.photobucket.com/albums/o...2/4e6d2283.jpg http://i121.photobucket.com/albums/o...2/8d1b1226.jpg http://i121.photobucket.com/albums/o...2/458528f3.jpg

11th May 2011, 08:25 AM	#5
mackinthebox diyAudio Member Join Date: Oct 2010	and apparently its 18vac and not 13...

11th May 2011, 08:38 AM	#7
mackinthebox diyAudio Member Join Date: Oct 2010	unfortunately i dont have the board with me, I will post some details on the black box when i get home from work in a couple hours

11th May 2011, 10:07 PM	#10
WSJ diyAudio Member Join Date: May 2009	The TA7318P data sheet has a circuit with a single +25 V supply. Toshiba TA7318P data sheet

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