Help with this circuit - it doesn't work. I had to substitute 2N3904 for Bel 187 because they are not available in the U.S.


http://forum.allaboutcircuits.com/attachment.php?attachmentid=62292&stc=1&d=1386341592

 

It wont. There is a mistake in the circuit. Then thyristors will not fire.

The thyristor requires a +ve trigger between M1 and Gate. The between condition is not met in the circuit.

Ramesh

 

Hi Ramesh, thanks for info - my electronics knowledge is limited, can you show me how to correct it?

 

Hi Ramesh, thanks for info - my electronics knowledge is limited, can you show me how to correct it?

Yes, but not in this forum

This forum policy prohibits playing around with non isolated power (or words to that effect).

Ramesh

 

You need to use an opto-triac MOC3020, to isolate from the mains supply like this

 

Perhaps it would be better to use relays. Depending of the switching speed of course

 

Yes, but not in this forum

This forum policy prohibits playing around with non isolated power (or words to that effect).

Ramesh

I don't think that circuit is a violation of the TOS; there's no transformerless power supply there and no LEDs connected to mains. It's just a circuit that switches mains voltage - a circuit to be careful with, but not a restricted topic.

6. Restricted topics. The following topics are regularly raised however are considered "off-topic" at all times and will result in Your thread being closed without question:

• Any kind of over-unity devices and systems
• Automotive modifications
• Devices designed to electrocute or shock another person
• LEDs to mains
• Phone jammers
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These are triacs and they don't need a connection between the gate and M1. They just need a trigger to the gate.

 

These are triacs and they don't need a connection between the gate and M1. They just need a trigger to the gate.

Did you find this circuit on the? Because it is lot of bad circuits ideas floating around in cyber space. And this clearly on of them, it is flawed in many ways

 

Yes, I did pull it from an electronics site, but it was a 6 light circuit and I downsized to 3. It seems so simple - the IC 1 & IC 2 circuit is cut and dried being used thousands of times! The triacs need a pulse to trigger and I figured that since I had to substitute Q1-3 that a change in resistor values was in order.