Hello all,
I'm dipping my toe in the waters of linear power supply design. Been playing with LTspice and came up with a voltage doubler circuit with some smoothing.
It seems to work, but I noticed that the voltage is increasing ever-so-slightly over long simulation runs.
For example, I have run the simulation for 2000 seconds. At the 5 second mark, it measures 26.17v and it steadily climbs to 26.392v at 2000 seconds.
It isn't a lot, but I've also run the simulation for 20000 seconds and indeed the voltage does continue to rise and rise.
I assume this is due to a design flaw. I am not surprised, but I would like some help trying to figure out why this circuit is doing this.
I'm dipping my toe in the waters of linear power supply design. Been playing with LTspice and came up with a voltage doubler circuit with some smoothing.
It seems to work, but I noticed that the voltage is increasing ever-so-slightly over long simulation runs.
For example, I have run the simulation for 2000 seconds. At the 5 second mark, it measures 26.17v and it steadily climbs to 26.392v at 2000 seconds.
It isn't a lot, but I've also run the simulation for 20000 seconds and indeed the voltage does continue to rise and rise.
I assume this is due to a design flaw. I am not surprised, but I would like some help trying to figure out why this circuit is doing this.
What circuit?
Hi I've attached the .asc.
Please don't laugh (well, laugh to yourself, perhaps).
Attachments
Just taking a stab at it... The circuit has no load, and voltage drops (ie, resistors) paired with the storage components. The voltage drops will get progressively smaller as the circuit approaches a sort of equilibrium nearing the doubled input ac voltage.
I'm not confident; this answer may be worthy of kudos or raspberries.
I'm not confident; this answer may be worthy of kudos or raspberries.
The circuit has no load, and approaches a sort of equilibrium nearing the doubled input ac voltage.
You're probably right. Add a load and it should stabilize quickly.
Thanks guys. I've added a load and it does seem to settle more quickly.
I'm surprised at how well this circuit works at smoothing ripple. Many of the component values are fairly flexible, too.
The drawback of the voltage doubler is that it places heavier demands on the power transformer.
What is the benefit of the 4k7 and 4μ7 across the output?
I honestly don't know. My circuit is a mish-mash of a bunch of stuff I found on the Internet.
I just removed them and replaced them with "wire" and the whole circuit falls apart (does not do what it is supposed to do).
Last edited:
That sounds like the wire shorting the output. Not good. Just remove them.I just removed them and replaced them with "wire" and the whole circuit falls apart (does not do what it is supposed to do).
I see them as having some filter effect, but whether it's anything meaningful I'm not so sure. The values look way too high.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Power Supplies
- Odd, slight voltage increase over long time periods