Convert 220VAC to 110VDC without transformer

[diepvu1805]

Hi all,
I want to convert from 220VAC/50Hz to 110VDC without transformer. I also don't want to use the voltage divider capacitor, resistor circuitry.
parametter as follow:
Vin: ~220VAC/50Hz
Vout: 110VDC
Iout: 12 - 20mA.
Non-isolated
Pls, suggest the good solution to me,
thank in advance,

 

[I_think]

can you specify the exact end usage?

 

[thylacine1975]

Probably the simplest approach would be a rectifier/cap, followed by a 110V zener driving an emitter follower. Not efficient, but cheap!
(And a ~5W heater at maximum Iout

 

[diepvu1805]

can you specify the exact end usage?

yes, Vout tolerance +/-5%

 

[picgak]

Bridge rectify to DC and use a resistor and 110V zener

 

[Tahmid]

You can use a transistor along with the diode-zener suggestions above to make the transistor dissipate the power rather than the resistor. You'll dissipate about 4W of power. Just use a decent sized heatsink. Or, you could just use a large power resistor capable of handling >> 4W power. Select a resistor such that the heat doesn't become too big an issue. You could "mount" the resistor on a heatsink as well, but if you're gonna do this anyways, I recommend using the transistor.

Hope this helps.
Tahmid.

 

[Orson Cart]

I know you said you didn't want to use this approach - but it is the most robust:

680nF capacitor (275Vac or 400VDC) a surge limiting resistor, say 100R 10W, then a bridge rectifier, say, 4 x 1N4007, then a limiting zener string, 39V zener, 5W, 3 in series to give you 117vDc max, zeners will dissipate 117 x 0.02 = 2,34 watt total (0.8 W each) at no load, less when you have a load.

This will give you your 110VDC at up to 20mA that you seek but will NOT be isolated from the mains.

p.s. a 50V/63V 1000uF cap across each zener will give you a smoother o/p, increase the 680nF mains cap for more o/p current.

The alternative is a small switchmode circuit using a TNY_switch device from Power integrations, they have some good circuits for buck converter implementations that will achieve what you want in a small space (with a small choke - not a transformer)

Regards, Orson.

 

[I_think]

I know you said you didn't want to use this approach - but it is the most robust:

680nF capacitor (275Vac or 400VDC) a surge limiting resistor, say 100R 10W, then a bridge rectifier, say, 4 x 1N4007, then a limiting zener string, 39V zener, 5W, 3 in series to give you 117vDc max, zeners will dissipate 117 x 0.02 = 2,34 watt total (0.8 W each) at no load, less when you have a load.

This will give you your 110VDC at up to 20mA that you seek but will NOT be isolated from the mains.

p.s. a 50V/63V 1000uF cap across each zener will give you a smoother o/p, increase the 680nF mains cap for more o/p current.

The alternative is a small switchmode circuit using a TNY_switch device from Power integrations, they have some good circuits for buck converter implementations that will achieve what you want in a small space (with a small choke - not a transformer)

Regards, Orson.

Exactly, Capasitive drop instead of resistive drop was in my mind. but you have to take care that surge voltages need to be handled properly.

also , use proper current limit resistor for surge , use a well calculated wattage of Zener diode. keep in mind a well calculated zener can work perfect as surge protector.

 

[tpetar]

Hi all,
I want to convert from 220VAC/50Hz to 110VDC without transformer. I also don't want to use the voltage divider capacitor, resistor circuitry.
parametter as follow:
Vin: ~220VAC/50Hz
Vout: 110VDC
Iout: 12 - 20mA.
Non-isolated
Pls, suggest the good solution to me,
thank in advance,

 

[Orson Cart]

I like the above solution, however the triac would need to have a very low holding current to keep it on for the light currents required by the original poster, at 110VDC, this could perhaps be overcome with the bridge rectifier and large-ish choke input filter, and a volt feedback system to vary the ON time of the triac.

 

[diepvu1805]

I want to keep Output at 110V +/-5% when Input change from 160VAC - 260VAC. Voltage 220VAC is typical.

 

[Orson Cart]

Is the 110VDC referenced to the neutral?

 

[diepvu1805]

Is the 110VDC referenced to the neutral?

yes, Output is 110VDC referenced to the neutral.

 

[Orson Cart]

A small switcher (flyback) would seem to be the most practical way, i.e. something from power integrations, a small flyback circuit where you can tie the neg o/p back to the neutral to give you a regulated 110VDC over the mains range you require, all other solutions will likely be quite bulky - and remember there is a limit of 5mA DC that you can draw from the AC supply, a switcher eliminates this problem by full wave rectifying the mains before processing, so that no net DC is drawn.

 

[FvM]

The circuit sketched in post #7 could be build with a half-wave rectifier, a shunt diode and double the capacitor value.