Go Down

Topic: How to control a lamps intensity (Read 7397 times) previous topic - next topic

Techone

@retrolefty

Quote
Again you will need to include a zero crossing detector for any chance of success when using thyristor class devices (triac/scr). They are switch devices and require proper gate trigger timing relative to the AC waveform


Thanks for the tips. I will look into that. And experiments with a lower AC voltage like 12 V from the secondary of a transformer.
And I agree with you.

smeezekitty




You have to agree with me with this : A light bulb don't react quickly. 


The reaction time does not matter if the average power is reduced.
I certainly do not suggest testing it with full AC line voltage. Testing it will full AC line voltage should only be done if the small scale is working good. Using the circuit I posted should work to PWM the AC wave instead of a triac. Unfortunately I do not have the parts to test it. The LTSpice simulation works good though.
I know that electronics simulations are hit and miss but I have attached the waveforms.
The first shows the input, output, and about 40% PWM duty signal. As you can see, the average power is reduced.
The second shows it with a constant input signal passing the AC near as-is.
RED is 60hz 4v input
GREEN is the ~1.5v control signal
BLUE is the output
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

Techone

OK... I do have parts here for the breadboard test. And I do have a scope.  And I have a sim call Circuit Wizard. I will try it on that too.

Your schematic is not too clear.  A redraw of the schematic will help me out. Did you have a BOM ? Parts lists ?

I hope the sim did not use the same ground.

I will tested it with a 12 V AC and use the Arduino for the PWM and see what happen.


smeezekitty



Your schematic is not too clear.  A redraw of the schematic will help me out. Did you have a BOM ? Parts lists ?

I attached another schematic. Its alittle better but still alittle unclear.
I do not have a BOM or parts list because the resistors, transistors and opto-isolators all depend on how much voltage and current you run through it.
Quote


I hope the sim did not use the same ground.

It did but thats to satisfy a silly simulator requirement.
Quote

I will tested it with a 12 V AC and use the Arduino for the PWM and see what happen.


Good luck and be-careful. Using AC around an Arduino even at low voltage can be a disaster if you are not careful.
Note: I may have drawn the opto-isolators backwards.
Note2: R1, R4 are relatively high value and R2 and R3 were relatively low value.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

Techone

FYI, in this tread, I post two link. It a "How a dimmer switch work" The OP did post a schematic - link . The Arduino is being use to act like a controller and to sync the PWM pulse with the AC wave and act like a dimmer switch waveform according to my understanding of the working of a dimmer switch. The only thing you have to do : Select the proper parts, and code it right.

BTW, I don't like the AC sensing circuit, I prefer the telephone ring detector circuit design. 


Go Up