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How to set reference for a sine wave with dc supply
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anishkgt:
That voltage is VPP at the secondary with an RMS of 35vac at the primary. The actual voltage at the secondary is VPP 8VA and RMS 2.6VAC. Can you please explain your circuit on the same pdf as i've attached, i find it hard to follow the previous.


--- Quote ---3.2 vac is not much to start a high current needed to spot weld.
--- End quote ---
But why would you consider this voltage as something to start a spot weld. Spot welding has low voltage and High current. Here the voltage is 2.6V RMS.
C:

I did not catch that you were driving the transformer with 35 VAC.

Using 35 VAC is a great idea during test.

To properly design something you need facts.

Need to know the power consumed by transformer with nothing connected to secondary_______

Using your 35 VAC source

Put a resistor in series with primary winding.

Source voltage = 35 Vac?
Resistor Voltage = ____
Transformer primary voltage = ____
Resistor value = ____

You will need to use resistor that handle the power dissipation.

With above values, can compute now load power use.

I do not want you to harm your 35 VAC source so for the following select a low resistor value that will not harm you 35 VAC if connected across this supply.
Use this resistor as above in series with primary.
Short the secondary of transformer.
Do above measurements again for this state.

while I look at last attachment.
 

C:

In SWP.pdf you have a box labeled Zero Cross Detect.

The source to this box is 9 Vac

In the data sheet for this AC opt-coulpler you will find some facts or graphs of the led's voltage & current.
You will also find the max safe current for this LED's
Peak voltage  12.72 = 9 Vac x 1.414
Resistor voltage = supply peak - LED forward voltage.

Resistor value = Resistor voltage / <Peek LED current

Now it is a good idea to stay away from limits and a higher value resistor will allow higher peak voltage from source.

Now looking at data sheet again you should find some facts about how the output transistor changes due to current through the LED.
From this you can compute what source input voltage will cause output to change.
Now there is no real need to use such high currents through the LED. Increasing series resistor value will lower LED current and cause a small change in turn-on voltage.

You show an AC input opto-coupler. So from 0 to X volts the output is off and above this voltage output is on.
With AC input this results in output being on except a short time around 0 Vac. Two on's per cycle of AC

anishkgt:
They work as of now. Just need some help with the contact sense part of the design. Did you manage to ad your version into it.
C:

To select a value for my R2 need facts about the microwave oven transformer.

Asked you to do some tests using your 35 Vac supply to get these facts two posts back.
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