Ok,
Need some help peeps please!
I have a “problem” & I am struggling with a solution, as I am stuck, in a rut, on my own, trying to come up with an answer.
I have a variable voltage source, 16V +/-25% ac, ish, so about 12 – 20V ac.
Source impedance is quite low, so it has quite a volt drop, but it can deliver up to around 10A.
The frequency varies from about 250Hz (12V) to about 1kHz (20V).
It’s also, not, a good smooth sine wave output.
I need to run about 60W of tungsten lighting @ 12V, just shy of 5A.
Not going to split hairs.
The lights must be on whenever the ac source is present.
The ac source when loaded with say 3-5A does become a bit more stable, but, it has an inherent defect in that if a fuse blows elsewhere it becomes totally un regulated and can reach 110V ac, so, it can & has destroyed connected electronic loads.
My caution is prompted by the lack of availability of replacement electronics, and the difficulty of retrofit.
It’s a cheap rubbish design, fundamentally, but, it’s not mine, I’m just landed with protecting the electronics & keeping the lamps lit correctly.
Now I have thought about rectifying the ac source then smoothing then using a dc/dc buck boost, as needed to get a nice 12V dc supply.
I can then protect the electronics against overvoltage with a crowbar.
However, I am struggling with a bridge rectifier as one of the legs of the ac is grounded to the dc –ve.
Solution eventually has to be dust & water tight & vibration resistant and to be used out of doors so quite a wide operational temperature range.
When I prototype on the actual circuit, I don’t get the results I’m expecting so I am overlooking something, and I can’t see it because I’m looking at the problem myself alone from the same angle all the time.
I’ve tried a full bridge rectifier, with the ac & dc legs common, not good.
Obviously shunting one diode.
I’ve tried a single diode, not good.
I’ve chucked a couple of 470muF caps in across the dc, and the ac side, in various combinations.
Mind the caps are only 50V, but, really they, should, be enough.
I am really overlooking something, but, I can’t see it.
Any ideas please?
Need some help peeps please!
I have a “problem” & I am struggling with a solution, as I am stuck, in a rut, on my own, trying to come up with an answer.
I have a variable voltage source, 16V +/-25% ac, ish, so about 12 – 20V ac.
Source impedance is quite low, so it has quite a volt drop, but it can deliver up to around 10A.
The frequency varies from about 250Hz (12V) to about 1kHz (20V).
It’s also, not, a good smooth sine wave output.
I need to run about 60W of tungsten lighting @ 12V, just shy of 5A.
Not going to split hairs.
The lights must be on whenever the ac source is present.
The ac source when loaded with say 3-5A does become a bit more stable, but, it has an inherent defect in that if a fuse blows elsewhere it becomes totally un regulated and can reach 110V ac, so, it can & has destroyed connected electronic loads.
My caution is prompted by the lack of availability of replacement electronics, and the difficulty of retrofit.
It’s a cheap rubbish design, fundamentally, but, it’s not mine, I’m just landed with protecting the electronics & keeping the lamps lit correctly.
Now I have thought about rectifying the ac source then smoothing then using a dc/dc buck boost, as needed to get a nice 12V dc supply.
I can then protect the electronics against overvoltage with a crowbar.
However, I am struggling with a bridge rectifier as one of the legs of the ac is grounded to the dc –ve.
Solution eventually has to be dust & water tight & vibration resistant and to be used out of doors so quite a wide operational temperature range.
When I prototype on the actual circuit, I don’t get the results I’m expecting so I am overlooking something, and I can’t see it because I’m looking at the problem myself alone from the same angle all the time.
I’ve tried a full bridge rectifier, with the ac & dc legs common, not good.
Obviously shunting one diode.
I’ve tried a single diode, not good.
I’ve chucked a couple of 470muF caps in across the dc, and the ac side, in various combinations.
Mind the caps are only 50V, but, really they, should, be enough.
I am really overlooking something, but, I can’t see it.
Any ideas please?
