Automatic night light (outdoor)

Discussion in 'General Electronics Chat' started by amgkyocera, Aug 28, 2015.

please what can i do to prevent the heat and actuate the relay?

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2. or is there another type of dropper, can i use! or cooling system!

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1. amgkyocera Thread Starter New Member

Aug 28, 2015
2
0
1- my 5watt 68k resistor heats too much! i have tried to lower the heat by putting 3 of the 5w 68k in series, that was ok!
however when i connect the load the output voltage dropped!! please what what can i do to settle it?

2-HYSTERISIS, the system is not able to actuate the relay

2. dl324 Distinguished Member

Mar 30, 2015
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What is the AC input voltage? What wattage is the zener?

3. amgkyocera Thread Starter New Member

Aug 28, 2015
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0
thanks, I am using a 1 watt zener diode and the AC voltage is 230v 50hz

4. #12 Expert

Nov 30, 2010
17,829
9,148
1) Your second transistor is drawn upside down.
1a) There is no relay in that circuit. It has an opto-isolator.
2) The main impedance to the current is the 225 capacitor. That means 722 ohms in series with 324 volts DC for a capability of passing .4488 amps into C2
3) the 68K resistor can allow .00327 amps and should show 0.73 watts of heating. A 5 watt resistor should not be in danger under those conditions. The 68K resistor is not at fault. Something else is wrong.
4) Using a 225 capacitor to limit the current to 137 times the amount of current allowed by the 68K resistor does not make sense to me. Besides that R4 is using up 0.0091 amps out of the available 0.00327 amps coming through the 68K resistor.
5) Trying to fire a MOC3021 with 0.00236 amps is too low. The BT136 needs 0.011 amps minimum to fire in quadrant three.

Summary: The number of illogical calculations shows that there is too much bad information for me to diagnose this circuit.

Anyone care to check my math to see if I missed something?

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5. ScottWang Moderator

Aug 23, 2012
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Welcome to the AAC forum.

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