TECH: Q*Bert sound/knocker 30v solution with switching power supply

[j***@sbcglobal.net]

Hey,
I was searching through the old RGVAC posts concerning how to obtain
the 30VDC on Q*Bert when using a switching PS. Your suggestion (below)
sounds great and I happen to have a spare 25 VAC transformer from Radio
Shack that I have left over from another project (tron sound project).
What I need to know is how do I build the rectifier bridge project that
James Sweet describes below. I'm new to this AC thing. The Tron sound
circuit was the first time I've ever explored AC things and I don't
know exactly how to change AC to DC. I have miscellaneous parts hanging
around here at the Family Fun Center where I work. Diodes and such and
maybe some rectifiers from old skee ball boards etc. I have no qbert
linear power supply board and would like to tinker with this today.
Thanks!
jaysun

Just finished restoring my Q*Bert cab back from a Ring King. I am going

to

use a switching power supply to drive it, which means I need to find a
source of power for the knocker and audio.
Looking for advice on what other people have used. All of the posts I

have

seen in Google, talk about using and alternate power supply, but they

never

describe what poeple have used!
Radio Shack has 30V, 1000Ma AC adaptor.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5F...

My concern with this is that the Knocker is fused at 1 amp and the sound
board is fused at 1.5 amps which is 2.5 amps in total. Will the game
overdrive this converter?
Radio Shack also has a transformer that will put out 25.2 Volts at 2 amps,

I

am not an electrical whiz, but from looking in Google, 25.2CT means center
tapped, which I understand to mean that it will have 3 wires coming out of
it, a ground, a positive and a negative. This would imply to me that this
is DC voltage, correct? If that is the case, could I just hook up the 30
volts from here to the knocker and Audio ro do I need to build som etype

of

circuit?

-----------------------------------------------------------------------------------

From: James Sweet
Date: Fri, Jan 2 2004 11:21 pm

Either should work just fine, the knocker only runs for a fraction of a
second, the sound board likely draws much less than it's fused for, the
filter capacitors will absorb the transients. If 1A proves to not be enough
the other transformer would work too, all you need is a rectifier bridge and
a filter cap. You can ignore the center tap and tape it off. All plain
transformers put out AC, a center tap just means that you can use the
secondary as two windings, so in this case you could have 2 12v outputs that
share a common ground, or 1 24v output.

[c***@rogers.com]

Changing AC to DC is simple. Use a Full Bridge recifier inputing the AC
into the 2 "~" ends of the recifier. And you will get that voltage out
on the "+" "-" ends. But depending on the requierments, you will need
to "Filter" or Cleanup the DC to remove any ripple.

Post by j***@sbcglobal.net
Hey,
I was searching through the old RGVAC posts concerning how to obtain
the 30VDC on Q*Bert when using a switching PS. Your suggestion (below)
sounds great and I happen to have a spare 25 VAC transformer from Radio
Shack that I have left over from another project (tron sound project).
What I need to know is how do I build the rectifier bridge project that
James Sweet describes below. I'm new to this AC thing. The Tron sound
circuit was the first time I've ever explored AC things and I don't
know exactly how to change AC to DC. I have miscellaneous parts hanging
around here at the Family Fun Center where I work. Diodes and such and
maybe some rectifiers from old skee ball boards etc. I have no qbert
linear power supply board and would like to tinker with this today.
Thanks!
jaysun

Just finished restoring my Q*Bert cab back from a Ring King. I am going

to

use a switching power supply to drive it, which means I need to find a
source of power for the knocker and audio.
Looking for advice on what other people have used. All of the posts I

have

seen in Google, talk about using and alternate power supply, but they

never

describe what poeple have used!
Radio Shack has 30V, 1000Ma AC adaptor.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5F...

My concern with this is that the Knocker is fused at 1 amp and the sound
board is fused at 1.5 amps which is 2.5 amps in total. Will the game
overdrive this converter?
Radio Shack also has a transformer that will put out 25.2 Volts at 2 amps,

I

am not an electrical whiz, but from looking in Google, 25.2CT means center
tapped, which I understand to mean that it will have 3 wires coming out of
it, a ground, a positive and a negative. This would imply to me that this
is DC voltage, correct? If that is the case, could I just hook up the 30
volts from here to the knocker and Audio ro do I need to build som etype

of

circuit?

-----------------------------------------------------------------------------------
From: James Sweet
Date: Fri, Jan 2 2004 11:21 pm

Either should work just fine, the knocker only runs for a fraction of a
second, the sound board likely draws much less than it's fused for, the
filter capacitors will absorb the transients. If 1A proves to not be enough
the other transformer would work too, all you need is a rectifier bridge and
a filter cap. You can ignore the center tap and tape it off. All plain
transformers put out AC, a center tap just means that you can use the
secondary as two windings, so in this case you could have 2 12v outputs that
share a common ground, or 1 24v output.