Voltage doubler is consist of two parts they are CLAMPER and RECTIFIER.
The most Voltage reducers consist of transformer and if they have rectifier it will be a REGULATOR.
While I am repairs a damaged device "Contactor" (It's a device changing the electricity which goes to the load automatically, It's consist of much components such as resistors,capacitors,relays,high voltage capacitors...etc). I saw a voltage reducer without using any transformer! Just using a high voltage capacitor in parallel with high resistor (1M) and a bridge rectifer, The output goes to the relay to doing the function.
I thought the capacitor is reduces the voltage in the same value of half frequency of the input signal (This answer from my teacher) But not sure what the calculations for this circuit! How i could calculate the exact value of the capacitor proportion with the required voltage value?
And more questions will comes in sequence in this discussion.
2V is rather low, is that running a solid-state relay? The LED in a solid state relay will hold/limit the voltage (as long as the current is held within specs).
You can make an AC [u]voltage divider[/u] with capacitors (or with a capacitor & resistor) by calculating the capacitive reactance, and that might be what's being done here.
That's called a capacitor dropper of capacitive dropper. The 1M resistor is just to discharge the capacitor when you turn it off (to not zapp yourself). For the purpose of the dropper it can be ignored. It just works because of the reactance of a capacitor. It's given by X = 1 / (2 x pi x f x C) in Ohms. So a fixed capacitor at a fixed frequency (like mains) has a fixed reactance. A 100nF capacitor @ 50Hz has a reactance of 1 / (2 x pi x 100n x 50) = 32kohm. It just acts a a resistor when calculating the current via ohms law. Most of the time a zener diode is used to clamp the voltage. Only there is no heat generated (or almost non) in the capacitor.
As far as I can see the image has nothing to do with the capacitive dropper but with a voltage doubler. Aka 2 V should be read as 2x V
DVDdoug:
2V is rather low, is that running a solid-state relay? The LED in a solid state relay will hold/limit the voltage (as long as the current is held within specs).
You can make an AC [u]voltage divider[/u] with capacitors (or with a capacitor & resistor) by calculating the capacitive reactance, and that might be what's being done here.
Sure it won't, This is for illustrating the circuit of voltage doubler. Not to run a relay.
septillion:
That's called a capacitor dropper of capacitive dropper. The 1M resistor is just to discharge the capacitor when you turn it off (to not zapp yourself). For the purpose of the dropper it can be ignored. It just works because of the reactance of a capacitor. It's given by X = 1 / (2 x pi x f x C) in Ohms. So a fixed capacitor at a fixed frequency (like mains) has a fixed reactance. A 100nF capacitor @ 50Hz has a reactance of 1 / (2 x pi x 100n x 50) = 32kohm. It just acts a a resistor when calculating the current via ohms law. Most of the time a zener diode is used to clamp the voltage. Only there is no heat generated (or almost non) in the capacitor.
As far as I can see the image has nothing to do with the capacitive dropper but with a voltage doubler. Aka 2 V should be read as 2x V
It seems logical but in this case only the current has reduced and the voltage on resistor terminal still the same.
Actually the circuit I seen it (the high voltage capacitor with bridge rectifier) was reducing the voltage from 220v AC to 24v DC.
I'm having a hard time understanding this.
It sounds vaguely like you are trying to describe an AC/DC rectifier but English is not your native language and something is being lost in the translation.
Please post a schematic, since that is a universal language or a link to a schematic of what you are talking about, and then maybe I can respond. At the moment, I'm going to say "no comprendo".
mi_ds:
It seems logical but in this case only the current has reduced and the voltage on resistor terminal still the same.
But you know Ohm's law don't you? You can't only reduce the current...
The capacitor is in series with the coil so it's just like putting a resistor in series with a coil. Only the rectifier providing DC instead of AC. And like I said, probably there's a zener in the design as well.
Just look it up. Big Clive has many great video's about capacitive droppers.
raschemmel:
I'm having a hard time understanding this.
It sounds vaguely like you are trying to describe an AC/DC rectifier but English is not your native language and something is being lost in the translation.
Please post a schematic, since that is a universal language or a link to a schematic of what you are talking about, and then maybe I can respond. At the moment, I'm going to say "no comprendo".
That's embarrassing
Simply, I have a circuit works like a voltage step-down transformer (from 220v to 24v) but without transformer. With the rectifier it would be a Regulator circuit.
septillion:
But you know Ohm's law don't you? You can't only reduce the current...
The capacitor is in series with the coil so it's just like putting a resistor in series with a coil. Only the rectifier providing DC instead of AC. And like I said, probably there's a zener in the design as well.
Just look it up. Big Clive has many great video's about capacitive droppers.
Yes, I know that it's require a zener diode. But here not used!
One BIG thing to be aware of where you are using a capacitor to drop the voltage instead of a transformer - there is no isolation from the mains (depending on how you get across it and how it is wired, the current may or may not be limited from one side or the other), but there is no isolation like a transformer provides. Be careful poking around in there :o
gpsmikey:
One BIG thing to be aware of where you are using a capacitor to drop the voltage instead of a transformer - there is no isolation from the mains (depending on how you get across it and how it is wired, the current may or may not be limited from one side or the other), but there is no isolation like a transformer provides. Be careful poking around in there :o
That's right but I think it's Worth the experience. Sure I will take a care if i got a full understanding of the principle.
As I said, it sounds like you are talking about a rectifier circuit.
The schematic you posted is for a FULL WAVE BRIDGE RECTIFIER POWER SUPPLY, with a SERIES RC CIRCUIT on the input (no values given so the impedance and phase shift cannot be calculated) and a 24V stepdown transformer on the output. I don't know why you are talking about a voltage doubler. I don't see any voltage doubler in that schematic. It is a garden variety 220V/24V AC power supply with capacitive reactance and
Parallel circuit[edit]
Parallel RC circuit
The parallel RC circuit is generally of less interest than the series circuit. This is largely because the output voltage V_{out} is equal to the input voltage V_{in} — as a result, this circuit does not act as a filter on the input signal unless fed by a current source.
With complex impedances:
I_R = \frac{V_{in}}{R},
and
I_C = j\omega C V_{in},
.
This shows that the capacitor current is 90° out of phase with the resistor (and source) current. Alternatively, the governing differential equations may be used:
I_R = \frac{V_{in}}{R}
and
I_C = C\frac{dV_{in}}{dt}
.
When fed by a current source, the transfer function of a parallel RC circuit is:
raschemmel:
As I said, it sounds like you are talking about a rectifier circuit.
The schematic you posted is for a FULL WAVE BRIDGE RECTIFIER POWER SUPPLY, with a SERIES RC CIRCUIT on the input (no values given so the impedance and phase shift cannot be calculated) and a 24V stepdown transformer on the output. I don't know why you are talking about a voltage doubler. I don't see any voltage doubler in that schematic. It is a garden variety 220V/24V AC power supply with capacitive reactance and
Yes, It's a rectifier but using series capacitor instead of transformer.
I don't know the values of the components. I need to know how I can calculate them.
I am was talking about voltage doubler because there are some connections between them and they are represents a transformer.
Simply, I need to design a rectifier which regulates (220V AC to 24V DC) without transformer.
Actually, I can put a zener diode after the rectifier to regulate the voltage. But i've seen a circuir do that without zener!
mi_ds:
Yes, I know that it's require a zener diode. But here not used!
I didn't say it requires a zener. Ohm's law works great without. It's very common to use a zener to clamp the voltage for example a micro controller or for when the relay isn't energized. But you don't NEED it. The relay coil is mostly just a resistor as well when it's powered on.
Just ignore R1 (it's so high it doesn't really matter) and replace C1 by it's equivalent resistor in your head. Does the circuit now looks weird to you?
