Showing posts with label ac. Show all posts
Showing posts with label ac. Show all posts
Monday, May 13, 2013
220V AC Lamp Toggle Switch Circuit
Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 12Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1A, IC1B, R2, R3 and C3 form a reliable bounce-free toggle switch operated by P1. R4 and C4, wired to pin #6 of IC1B reset the circuit (lamp off) when power supply is applied. IC1C and IC1D wired in parallel act as a buffer, driving the Gate of the Triac through R5. Parts:
R1 = 470R
R2 = 10K
R3 = 100K
R4 = 100K
R5 = 1K
C1 = 330nF-400V
C2 = 100uF-25V
C3 = 100nF-63V
C4 = 10uF-25V
D1 = 1N4007
D2 = 1N4007
D3 = BZX79C12
D4 = TIC206M
IC1 = 4011 NAND Gate
Notes:
* The circuit can be wired permanently to the mains supply as current drain is negligible.
* Due to transformerless design there is no heat generation.
* Low Gate-current Triacs are recommended.
* Obviously, other appliances can be powered in place of a lamp, provided their power dissipation does not exceed about 400W @ 230V
* 110-120Vac operation is easily obtained by simply changing C1 value to 680nF 250V. No further changes are necessary.
* In some cases, e.g. when the controlled device is far from the toggle switch, a pilot LED could be necessary for monitoring purposes. If so, disconnect pin #10 of IC1C from pin #11 of IC1D and wire a LED and its 1K series current limiting resistor across pin #10 of IC1C and negative supply.
* Warning! The circuit is connected to 230Vac mains, so some parts in the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged in and enclose it in a plastic box.
* P1 will SPST Pushbutton
Saturday, April 13, 2013
Mains AC Xenon Tube Flasher Circuit
The article discusses a very simple yet amusing mains operated xenon tube flasher circuit using ordinary electronic components.
The circuit was taken from one of the old elektor electronics magazine and it is indeed a very cute little circuit which may be used for creating high intensity lighting effects during festivals, parties and fun gatherings.
The circuit may be understood by referring to the diagram and with the following explanations:
Diodes D1 and D2 along with the capacitors C1 and C2 form a voltage doubler circuit which creates a voltage level twice the value of the input voltage (across C1/C2).
Resistors R4 along with R5 and P1 provides the gate current to the triac so that it can fire for the required actions.
However the triac is unable to fire until the voltage reaches above the diac firing voltage which is around 60 volts (due to D3/D4).
Once this happens the triac triggers, inducing a momentary pulse inside the primary winding of the pulse transformer via C3.
This in turn jumps a high voltage pulse into the secondary of the transformer which is connected to the trigger wire of the xenon bulb.
The xenon bulb triggers due to the above actions passing the entire voltage across C1/C2 through it.
This generates a blinding arc light inside the tube, producing the required high intensity flash.
However once the tube fires C1/C2 completely discharges making the gate voltage of the triac fall to zero switching OFF the xenon bulb instantly
The whole circuit returns to its original condition until C1/C2 charges up again and repeats the cycle.
Thus the flashing keeps repeating as long as mains power stays connected at the input.
Xenon Tube
As the name suggests, its a tube filled with inert xenon gas. A metal ring is attached toward the anode side of the tube which becomes the gate trigger point of the device. This ring is terminated with a wire so that it can be connected with s pulse source.
When a high voltage is set across the anode/cathode pins of the tube and a pulse applied across the trigger gate wire and cathode, the tube gets charged up and allows the whole voltage across its Anode.cathode to pass through creating an intense arc lighting inside the tube due to the passage of the high speed electrons through the xenon gas.
Any standard xenon tube can be used here, preferably the ones which are used in electronic cameras.
The transformer
The transformer may be built by winding 100 turns of 36 SWG wire over a tiny ferrite core. This becomes the secondary winding (A to B)
And about 10 turns of 22 SWG over the above winding. This becomes the primary winding of the transformer (A to C)
The circuit was taken from one of the old elektor electronics magazine and it is indeed a very cute little circuit which may be used for creating high intensity lighting effects during festivals, parties and fun gatherings.
The circuit may be understood by referring to the diagram and with the following explanations:
Diodes D1 and D2 along with the capacitors C1 and C2 form a voltage doubler circuit which creates a voltage level twice the value of the input voltage (across C1/C2).
Resistors R4 along with R5 and P1 provides the gate current to the triac so that it can fire for the required actions.
However the triac is unable to fire until the voltage reaches above the diac firing voltage which is around 60 volts (due to D3/D4).
Once this happens the triac triggers, inducing a momentary pulse inside the primary winding of the pulse transformer via C3.
This in turn jumps a high voltage pulse into the secondary of the transformer which is connected to the trigger wire of the xenon bulb.
The xenon bulb triggers due to the above actions passing the entire voltage across C1/C2 through it.
This generates a blinding arc light inside the tube, producing the required high intensity flash.
However once the tube fires C1/C2 completely discharges making the gate voltage of the triac fall to zero switching OFF the xenon bulb instantly
The whole circuit returns to its original condition until C1/C2 charges up again and repeats the cycle.
Thus the flashing keeps repeating as long as mains power stays connected at the input.
As the name suggests, its a tube filled with inert xenon gas. A metal ring is attached toward the anode side of the tube which becomes the gate trigger point of the device. This ring is terminated with a wire so that it can be connected with s pulse source.
When a high voltage is set across the anode/cathode pins of the tube and a pulse applied across the trigger gate wire and cathode, the tube gets charged up and allows the whole voltage across its Anode.cathode to pass through creating an intense arc lighting inside the tube due to the passage of the high speed electrons through the xenon gas.
Any standard xenon tube can be used here, preferably the ones which are used in electronic cameras.
The transformer
The transformer may be built by winding 100 turns of 36 SWG wire over a tiny ferrite core. This becomes the secondary winding (A to B)
And about 10 turns of 22 SWG over the above winding. This becomes the primary winding of the transformer (A to C)
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