dual-output power supply from 230v mains

[Hybzy]

Hi guys, I'm new to this forum, and hoping you can help me.

I have built a marx generator for some research I am doing, and the mains power supplying it is 230 volts. I need to have a separate circuit within the unit which is being powered by the main, however only around 10v - 15v roughly.

I was wondering what the best way to do this would be. Would I be able to use a 7815, and instead of bleeding the voltage to ground, just have it run to the remainder of the circuit? or would the voltage be too high for a standard regulator?

I wanted to get away with a simple linear method, without the need for building a switched-mode.

Normally this thing isn't too complicated, but I'm a little confused, because the marx generator itself is an open circuit, so impedance is infinite, and I'm unsure on how to build a voltage-divider.

Thankyou in advance for your assistance.
Also, not sure if this topic belongs here, but I had a quick browse, and it seemed to be the most fitting place

 

[IanP]

Take a look at the attached circuit ..
This supply uses no heavy step down transformer and has an extremely low parts count. The circuit can be built very small and can supply small currents for small projects. The major downfall of this supply is that it is not isolated from the AC line and can only supply small currents ..
C1 can be estimated from the basic equasion X[c]=230V/I
where X[c] is the reactive part - so (almost) no heat - = 1/[ 2ΠfC]
The Zener ≈ 15V and smoothing cap ≈ 100µF ..
But all the above applies only when you don't need much current and the isolation is not an issue ..

Rgds,
IanP

 

[nashwan]

hi
Ianp u must here add small resistore in series with c1 to protect BR1

another circuit like this may be use output voltage here about 15v d.c

 

[nashwan]

hi
Ianp u must here add small resistore in series with c1 to protect BR1

another circuit like this may be use output voltage here about 15v d.c

 

[FANT]

Be very, very, very careful with such a cicuits, because the mains is not insulated from the ciorcuit and anybody will touch it will be shocked by current.
THERE IS A REAL RISK OF ELECTROCUTATION AND DEATH.
use a transformer and a normal bridge, followed by a 78XX.
Don't risk your life.
Or even better buy a market power supply for one or two Euro.
Or ( the last ) use a recharger for mobile phones or even two in series, usually the voltage is in the 6 Volt range.

Mandi

 

[Hybzy]

Thanks for the helps guys.

IanP, I'll definitely give that a shot. The Marx generator itself only draws about 80mA, but I've yet to design the other circuit. The 15V will just be used to power a 3x 7seg LED voltmeter, so hopefully that circuit allows enough current.

Isolation isn't an issue, as the generator has an output of 200kV, so it's quite dangerous anyway, and is going to be only used by myself for research purposes. It will all be enclosed so it's unable to touch any of the circuit from outside.

Cheers.