Would you suggest below circuit? Will it work for a long time? What are the advantage and disadvantages of this circuit?
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2\$\begingroup\$ ...real time application For EEs "real time" usually refers to a processor doing things in "real time", meaning doing it immediately. What you mean is "continuous use" or "using it 24/7". The fact that even in cheap (Chinese) commercial products, you will find a slightly more complex (expensive!) circuit means that this circuit is not a good choice. If it was, then for sure those products would use it. \$\endgroup\$– BimpelrekkieCommented Mar 18, 2021 at 14:24
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1\$\begingroup\$ Do people even still use LDRs? Does anyone still make them? Are they even still legal considering the cadmium content? \$\endgroup\$– HearthCommented Mar 18, 2021 at 15:21
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\$\begingroup\$ Unpredictable behavior. May work, may not. \$\endgroup\$– user263983Commented Mar 18, 2021 at 15:25
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\$\begingroup\$ @Hearth Yes, they're still made and are available off-the-shelf in countries with more laissez-faire treatment of hazardous substances such as the US and China. I believe the EU's limited exemption on them (for pro audio equipment optocouplers) expired Dec. 31, 2013. \$\endgroup\$– Spehro 'speff' PefhanyCommented Mar 18, 2021 at 15:29
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\$\begingroup\$ @SpehroPefhany I haven't seen them in the US in years and years, but perhaps they're still used by hobbyists--I've certainly never used them in anything I designed. \$\endgroup\$– HearthCommented Mar 18, 2021 at 15:32
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2 Answers
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Disadvantages: For one, it won't typically work at all. Typical gate trigger current for the BT136 is 2.5mA/5mA in quadrants I and III respectively.
The 220K resistor will conduct 1.4mA at the very peak of a 220V waveform, insufficient to turn the triac on in either quadrant. At 110V or at cold temperatures or with a particularly numb sample of BT136 things are considerably worse.
Advantages? I guess it conserves energy.
answered Mar 18, 2021 at 14:23
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\$\begingroup\$ If i use 100K Resistor, will it work ?. it gives 2.3mA. My worries are, is there any possibility to LDR burn out in 230vAC and will it gives proper output? \$\endgroup\$ Commented Mar 18, 2021 at 14:49
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\$\begingroup\$ Is 2.3mA >> 5mA? I don't think it will damage the LDR, the gate-MTI junctions are across it. It will just sit there consuming a bit of current. \$\endgroup\$ Commented Mar 18, 2021 at 15:23
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220k will not work. I used 220 R (ohm) ressistor then worked. Can't beleve. I thought it will burn. But no.Triac is same.
