220 Volts Flashing Lamps

Especially designed for Christmas tree lamps Replaces old thermally-activated switches

This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1,R2 & C1. To change flashing frequency dont modify R1 and R2 values: set C1 value from 100 to 2200µF instead.

Circuit diagram :

220 Volts Flashing Lamps Circuit Diagram

Best performances are obtained with C1=470 or 1000µF and R4=12K or 10K. Due to low consumption of normal 10 or 20 lamp series-loops intended for Christmas trees (60mA @ 220V typical for a 20 lamp series-loop), very small and cheap SCR devices can be used, e.g. C106D1 (400V 3.2A) or TICP106D (400V 2A), this last and the suggested P0102D devices having TO92 case.

Parts List:

R1 100K 1/4W Resistor
R2,R5 1K 1/4W Resistors
R3,R6 470R 1/4W Resistors
R4 12K 1/4W Resistor
C1 1000µF 25V Electrolytic Capacitor
D1-D4 1N4007 1000V 1A Diodes
D5 P0102D 400V 800mA SCR
Q1 BC327 45V 800mA PNP Transistor
Q2 BC337 45V 800mA NPN Transistor
PL1 Male Mains plug
SK1 Female Mains socket

Note:

For proper operation its absolutely necessary to employ high Gate-sensitive SCRs.

If you are unable to find these devices you can use Triacs instead. In this case the circuit operates also with relatively powerful devices. A recommended Triac type is the ubiquitous TIC206M (600V 4A) but many others can work.Note that in spite of the Triac, diode bridge D1-D4 is in any case necessary.

This circuit was awarded with publication in ELECTRONICS WORLD "Circuit Ideas", June 2000 issue, page 458

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Flashing LED Battery status Indicator

Signals when an on-circuit battery is exhausted 5V to 12V working voltage

A Battery-status Indicator circuit will also be useful, mainly to observe portable Test-gear units and equivalent devices. LED D1 flashes to apparel the customers attention, signaling that the circuit is operating, so it's going to no longer be left on by using mistake. The circuit generates about two LED flashes per second, however the mean present drawing might be about 200µA. Transistors Q1 and Q2 are wired as an unusual complementary astable multivibrator: each are off 99% of the time, saturating best when the LED illuminates, in this case contributing to keep very low current consumption. 

Circuit diagram :

Flashing-LED Battery-status Indicator Circuit Diagram

The circuit will work with battery supply voltages within the 5 - 12V vary and the LED flashing will additionally be stopped at the desired battery voltage (comprised within the four.8 - 9V worth) by way of adjusting Trimmer R4. This vary can also be modified via altering R3 and/or R4 worth relatively.

When the battery voltage methods the onerous price, the LED flashing frequency will fall suddenly to alert the consumer. Obviously, when the battery voltage has fallen under this price, the LED will stay completely off. To maintain steady the exhausting voltage price, diode D1 was once brought to compensate Q1 Base-Emitter junction changes in temperature. The use of a Schottky-barrier device (e.g. BAT46, 1N5819 and the like) for D1 is mandatory: the circuit is no longer going to work if a common silicon diode just like the 1N4148 is used as an alternative.

Parts :

R1,R7__________220R  1/4W Resistors
R2_____________120K  1/4W Resistor
R3_______________5K6 1/4W Resistor
R4_______________5K  1/2W Trimmer Cermet or Carbon
R5______________33K  1/4W Resistor
R6_____________680K  1/4W Resistor
R8_____________100K  1/4W Resistor
R9_____________180R  1/4W Resistor
C1,C2____________4µ7  25V Electrolytic Capacitors
D1____________BAT46  100V 150mA Schottky-barrier Diode
D2______________LED  Red 5mm.
Q1____________BC547   four5V 100mA NPN Transistor
Q2____________BC557   45V 100mA PNP Transistor
B1_______________5V to 12V Battery provide
Notes :

• Mean current drawing of the circuit can be lowered further on by using elevating R1, R7 and R9 prices.

Source : Red Circuits

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