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[Marcel]

Simplest explanation for multiplier circuits is it's a bit like voltage stacking.
We all know how with a diode and a cap we can convert AC into DC, well, if we do it multiple times in (theoretical) parallel and then put all the resultant DC voltages in series you can achieve higher DC voltages from lower AC voltages.

The mathematics and the trickery pokery of reality are a lot more complex but that only really concerns the designers... for us we just need to be able to recognise the basic circuit and to know what voltage we can expect at the output... Usually you can recognise it as an AC power signal of some sort going to a bunch of diodes (often 3 or more) in series with appropriately voltage'd caps (usually tied to chassis/earth) connected between every diode with a higher voltage needing 'load' at the end.

One thing to remember is only voltage is multiplied...Power remains the same.... Discounting any losses in the circuit If we have 12v at 1A at the input to the multiplier then if we multiply up to 24V we can only consume 0.5A, and at 48V we will have 0.25A at our disposal, and if we multiply up to 96V then the maximum theoretical current we can draw is only 0.125A (12V x 1A = 96V x 0.125A = 12W assuming nil losses). In reality due to losses and the effects of 'loading' the multiplier to 96V will probably only supply a maximum of about 0.1A before drastically dropping of in the higher voltage it can supply.

[DrNomis_44]

Simplest explanation for multiplier circuits is it's a bit like voltage stacking.
We all know how with a diode and a cap we can convert AC into DC, well, if we do it multiple times in (theoretical) parallel and then put all the resultant DC voltages in series you can achieve higher DC voltages from lower AC voltages.

The mathematics and the trickery pokery of reality are a lot more complex but that only really concerns the designers... for us we just need to be able to recognise the basic circuit and to know what voltage we can expect at the output... Usually you can recognise it as an AC power signal of some sort going to a bunch of diodes (often 3 or more) in series with appropriately voltage'd caps (usually tied to chassis/earth) connected between every diode with a higher voltage needing 'load' at the end.

One thing to remember is only voltage is multiplied...Power remains the same.... Discounting any losses in the circuit If we have 12v at 1A at the input to the multiplier then if we multiply up to 24V we can only consume 0.5A, and at 48V we will have 0.25A at our disposal, and if we multiply up to 96V then the maximum theoretical current we can draw is only 0.125A (12V x 1A = 96V x 0.125A = 12W assuming nil losses). In reality due to losses and the effects of 'loading' the multiplier to 96V will probably only supply a maximum of about 0.1A before drastically dropping of in the higher voltage it can supply.

Yep, but since the typical 12AX7 Triode gain-stage circuit will only draw maybe up to 1mA of current at best from the HT supply, a limit of .1A is probably nothing to worry about, so, to power a circuit that uses one 12AX7 valve, using the Voltage Multiplier circuit to generate the +HT supply, we would only need a regulated power supply to generate +12.6V DC for the heater, and +15V DC for the Voltage Multiplier.

That means we could use something like a 16V AC/1.25A plugpack adaptor to power the regulated power supply circuitry together with a basic Bridge-Rectifier and filter cap to rectify the 16V AC to raw DC.

[JohnH]

Simplest explanation for multiplier circuits is it's a bit like voltage stacking.
We all know how with a diode and a cap we can convert AC into DC, well, if we do it multiple times in (theoretical) parallel and then put all the resultant DC voltages in series you can achieve higher DC voltages from lower AC voltages.

The mathematics and the trickery pokery of reality are a lot more complex but that only really concerns the designers... for us we just need to be able to recognise the basic circuit and to know what voltage we can expect at the output... Usually you can recognise it as an AC power signal of some sort going to a bunch of diodes (often 3 or more) in series with appropriately voltage'd caps (usually tied to chassis/earth) connected between every diode with a higher voltage needing 'load' at the end.

One thing to remember is only voltage is multiplied...Power remains the same.... Discounting any losses in the circuit If we have 12v at 1A at the input to the multiplier then if we multiply up to 24V we can only consume 0.5A, and at 48V we will have 0.25A at our disposal, and if we multiply up to 96V then the maximum theoretical current we can draw is only 0.125A (12V x 1A = 96V x 0.125A = 12W assuming nil losses). In reality due to losses and the effects of 'loading' the multiplier to 96V will probably only supply a maximum of about 0.1A before drastically dropping of in the higher voltage it can supply.

Ok, that makes some sense to me. I still have to think about it a bit I think...

[DrNomis_44]

Ok, that makes some sense to me. I still have to think about it a bit I think...

No worries, take your time cause it is a bit hard to understand at first, I went through the same learning-process when I first started out in electronics.

[JohnH]

No worries, take your time cause it is a bit hard to understand at first, I went through the same learning-process when I first started out in electronics.

Yeah, it's pretty mind bending. My brother summed up my feelings perfectly at a gig a few months back - we were both pretty drunk and standing at the side of the stage and apropos of nothing he just kind of shrugged, shook his head and exclaimed 'but what even IS electro-magnetism?!?'

[DrNomis_44]

Yeah, it's pretty mind bending. My brother summed up my feelings perfectly at a gig a few months back - we were both pretty drunk and standing at the side of the stage and apropos of nothing he just kind of shrugged, shook his head and exclaimed 'but what even IS electro-magnetism?!?'

Scientists have theorized about what Electro-Magnetism is, but personally I think we are barely scratching the surface with our current understanding.

[Simon Barden]

Scientists have theorized about what Electro-Magnetism is, but personally I think we are barely scratching the surface with our current understanding.

Very good, Doc.

Don't forget that as you increase the voltage, it becomes more dangerous to mess about with. You need to be sure that all your wires and components are suitably rated for that voltage. Each component in the multiplier might not have a large voltage across it, but the voltage with respect to ground is increasing with each step.

[DrNomis_44]

Very good, Doc.

Don't forget that as you increase the voltage, it becomes more dangerous to mess about with. You need to be sure that all your wires and components are suitably rated for that voltage. Each component in the multiplier might not have a large voltage across it, but the voltage with respect to ground is increasing with each step.

Good point, and you're right about that...pun not necessarily intended but it did work out pretty well in the end I must say.