Capacitive voltage divider power supply

Thread Starter

jymmm

Joined Jul 10, 2018
3
Hi Forum,

I'm just messing around with a little led indicator circuit to act as an 'on' light. I thought to use a cap divider circuit to limit the current and drop the voltage down (see attached). But I'm not sure on the placement of the inrush resistor R4 and the discharging resistor R3. Any thoughts appreciated.
Jim.
 

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crutschow

Joined Mar 14, 2008
24,724
R4 placement is fine as an inrush limiter.

You don't need R3 or C3.

Just select the value for C2 to give the LED current you want.
 

Thread Starter

jymmm

Joined Jul 10, 2018
3
Is there no benefit in dropping the voltage down for the LEDs? As well as bleeding the caps when switched off?
 

crutschow

Joined Mar 14, 2008
24,724
Is there no benefit in dropping the voltage down for the LEDs? As well as bleeding the caps when switched off?
Can't think of any.

The LED is basically a current operated device.
If you control the current to the desired value (by using the proper capacitor value), the voltage will be whatever the LED forward drop voltage is.

What's the reason to bleed the caps when switched off?
 

Thread Starter

jymmm

Joined Jul 10, 2018
3
I guess i'm just over egging the pudding on this one.

I'll drop the cap divider and the bleed R.

Thanks for your input.
 
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