It may be because of current interrupting in brushes system.
Connect incandescent 12 V bulb parallel to motor,
and see what will happens.

Just busy building a new schematic. I seem to have found the issue. Will test it and let you know how it goes!

Thanks!

 

Does this look good? If so, what diode do you think I need for "D1 - ???"?
S1 is a dual rocker switch with three positions.

Thanks again all.

 

It will not work. Transformers do not work with DC. What is the value of the load resitor ? I must be low enough to provide the holding current and NOT so low as to exceed the current rating of the SCR and the diode D1. I don't think you need the diode D1
Les.

 

It will not work. Transformers do not work with DC. What is the value of the load resitor ? I must be low enough to provide the holding current and NOT so low as to exceed the current rating of the SCR and the diode D1. I don't think you need the diode D1
Les.

The "transformer" is just a buck dc converter and it does charge the capacitor. Not an ac transformer.

The LOAD is just an electromagnetic coil.

I will test it soon, and let you know how it goes.

 

Does this look good?

 

For example, read post #45

ADDED: Bulbs U2-U4 can be eliminated, when using DC-DC converter.
High Voltage DC-DC Boost Converter Step Up to Output 300v-1200v 400V 900V 1000V Adjustable Power PSU Module Board Input 3V-5V
Price $ 2.40, Delivery $ 0.86.

 

What is the end goal of this? What does the inductor do?

 

Does this look good?

What I understand from the circuit, you push the button to enable the step up converter, charge the capacitor, and then trigger the SCR?
If I am correct, the circuit should work.

 

What I understand from the circuit, you push the button to enable the step up converter, charge the capacitor, and then trigger the SCR?
If I am correct, the circuit should work.

Yes, that is exactly correct. I have just wired that circuit up, but the thyristor does not trigger.
UPDATE: I think I have just found the issue. The negatives were not linked up correctly so that the 12V negative and 400V negative were not joined.
Trying to fix this now!

 

Thanks to all of you I have now managed to get the thyristor to trigger on the main 400V circuit!!!

I really do appreciate everyones help in this. Thank you!

 

Can anybody just let me know what value diode I need for this schematic? Where "D1 - ???" is?
I am having 400V back current getting down into the 12V system and it's messing things up a little!
Otherwise all is working correctly now!

 

If you install that diode, the gate trigger current cannot flow!
Remove it and connect the grounds together.

 

If you install that diode, the gate trigger current cannot flow!
Remove it and connect the grounds together.

I have an issue with 400V current coming back down the into the 12V supply. How can I stop this?
It is coming up through the 12V inlet into the 12V - 400V DC buck converter. So would this work instead?

 

Try a diode in either or both of the locations suggested in this diagram. I suspect somehow the capacitor can discharge weakly back into the DC-DC converter - its probably not expecting a big output cap.

 

Try a diode in either or both of the locations suggested in this diagram. I suspect somehow the capacitor can discharge weakly back into the DC-DC converter - its probably not expecting a big output cap.

View attachment 345345

Thanks, that makes sense to put them in there.
What size diode would I need for both those locations?
Thanks!

 

something like the common 1N4007 (1000V, 1A) would suffice for either location.

 

something like the common 1N4007 (1000V, 1A) would suffice for either location.

Thanks, I will try that.

 

It works! Thanks, those diodes have fixed the back current issue.

Thank you all, I think this finishes this thread!

 

For anybody else viewing this thread here is the final working schematic: