ok, so moving on from the voltage meter query...i'm wanting to build a version of the Brian May Deacy amp using this layout

https://paulinthelab.blogspot.com/2012/06/brian-may-deacy-amplifier-stripboard.html

but (as i understand it, at least) it's 18v centre positive, and i'm running from a 9v centre -ve power supply, so, the question is...

charge pump -> voltage inverter -> voltage sag

or

voltage inverter -> charge pump -> voltage sag

or is there an easier way?

my brain has lots of ideas, but somewhere between conception and realisation it checks out and goes for a beer...

The circuit says it's for  9V, POSITIVE GROUND (like a Ge fuzz face).  You can just use what you have, watch your + and - ! 

If you wanted to run on 18V (check that components can handle it, I did not),  I'd get an 18V wall wart, personally, and make sure I had adequate filtering/regulation, as it likely puts out 20-something volts unloaded unless it's made specifically for audio use (measure the output).   

I'd rather not mess with the charge pump, given that the Deacy layout is for positive ground - but I'm sure someone a bit more knowledgeable about charge pumps will come by and suggest a way to set up the grounds so it could work!   But again, not needed...

If you were using an 18V 'wart, it's easy - the + is treated as ground, - is the supply, and off you go.  As stated, you have to only use the 1 power supply and not use a daisy chain, etc!   But - one more time - you Don't NEED 18V here...

"it's also worth mentioning about the whole positive ground thing, back in the olden days they used to have positive grounding rather than the more normal (now) negative ground. it's okay though even though it says -9v on the stripboard all you have to do is connect the negative to the -9v and the positive to the ground and it will work - this amplifier was originally battery powered so using pedals wasn't an issue however should you wish to use a power supply then you need to use a separate one to any pedals you have plugged into it or it won't work"

.

Quote from: GibsonGM on April 20, 2025, 12:55:18 PMThe circuit says it's for  9V, POSITIVE GROUND (like a Ge fuzz face).  You can just use what you have, watch your + and - ! 

If you wanted to run on 18V (check that components can handle it, I did not),  I'd get an 18V wall wart, personally, and make sure I had adequate filtering/regulation, as it likely puts out 20-something volts unloaded unless it's made specifically for audio use (measure the output).   

I'd rather not mess with the charge pump, given that the Deacy layout is for positive ground - but I'm sure someone a bit more knowledgeable about charge pumps will come by and suggest a way to set up the grounds so it could work!  But again, not needed...

If you were using an 18V 'wart, it's easy - the + is treated as ground, - is the supply, and off you go.  As stated, you have to only use the 1 power supply and not use a daisy chain, etc!  But - one more time - you Don't NEED 18V here...

"it's also worth mentioning about the whole positive ground thing, back in the olden days they used to have positive grounding rather than the more normal (now) negative ground. it's okay though even though it says -9v on the stripboard all you have to do is connect the negative to the -9v and the positive to the ground and it will work - this amplifier was originally battery powered so using pedals wasn't an issue however should you wish to use a power supply then you need to use a separate one to any pedals you have plugged into it or it won't work"

i swear i've looked at this and it said 18v??? god knows what i've been looking at then 

so all i need to do is connect the ground from the power in to the +ve instead of the -ve...right?


if that's the case i'm game on

Yes - it says " -9V", which would be your power supply ground ( - ), and your power supply + goes to 'GND'...it takes some getting used to.  Positive grounds aren't too common (anymore!); they're from early transistor days when all we had were PNPs.   And ground is really just a common point of reference for the circuit; we won't go there today, though!     

How you connect it is up to you - the board doesn't care if your supply is center positive or negative. You can wire the jack appropriately at the PCB, and just use that power supply for positive ground 9V circuits. Label the wall wart so you don't plug it into any non-compatible pedals! 

Check back here if it makes a hum (insufficient filtering), in case the wall wart isn't really meant for audio purposes. But get this going first, that's another topic

Quote from: abacab666 on April 20, 2025, 01:54:30 PM

Quote from: GibsonGM on April 20, 2025, 12:55:18 PMThe circuit says it's for  9V, POSITIVE GROUND (like a Ge fuzz face).  You can just use what you have, watch your + and - ! 

If you wanted to run on 18V (check that components can handle it, I did not),  I'd get an 18V wall wart, personally, and make sure I had adequate filtering/regulation, as it likely puts out 20-something volts unloaded unless it's made specifically for audio use (measure the output).   

I'd rather not mess with the charge pump, given that the Deacy layout is for positive ground - but I'm sure someone a bit more knowledgeable about charge pumps will come by and suggest a way to set up the grounds so it could work!  But again, not needed...

If you were using an 18V 'wart, it's easy - the + is treated as ground, - is the supply, and off you go.  As stated, you have to only use the 1 power supply and not use a daisy chain, etc!  But - one more time - you Don't NEED 18V here...

"it's also worth mentioning about the whole positive ground thing, back in the olden days they used to have positive grounding rather than the more normal (now) negative ground. it's okay though even though it says -9v on the stripboard all you have to do is connect the negative to the -9v and the positive to the ground and it will work - this amplifier was originally battery powered so using pedals wasn't an issue however should you wish to use a power supply then you need to use a separate one to any pedals you have plugged into it or it won't work"

i swear i've looked at this and it said 18v??? god knows what i've been looking at then 

so all i need to do is connect the ground from the power in to the +ve instead of the -ve...right?


if that's the case i'm game on

I've built a couple of this Deacy amp, and I suggest you to use it battery powered (as Mr. May did) or building the battery simulator that you can find in Paul's blog. Lot of Deacy tone in Queen's songs are recorded with low battery charge.

Quote from: abacab666 on April 20, 2025, 11:51:27 AMok, so moving on from the voltage meter query...i'm wanting to build a version of the Brian May Deacy amp using this layout

https://paulinthelab.blogspot.com/2012/06/brian-may-deacy-amplifier-stripboard.html

but (as i understand it, at least) it's 18v centre positive, and i'm running from a 9v centre -ve power supply, so, the question is...

charge pump -> voltage inverter -> voltage sag

or

voltage inverter -> charge pump -> voltage sag

or is there an easier way?

my brain has lots of ideas, but somewhere between conception and realisation it checks out and goes for a beer...

Even though you don't need it, IIRC it draws over 150ma so you're not running it off any standard inverter like a LT1054

This looks like a typical transistor radio audio section from the 1950's.  If you can get good transistors (and the two output transistors should be matched), it should sound OK.  Beware of the negative feedback going around the inverter transformer - there could be low frequency instability as well as high frequency instability because of the phase shifts at low frequencies and high frequencies.