Recent content by GlynnHeeswijk

Thanks. From what I understand MOTs tend to be a bit too small for the task. I was thinking of making a bigger choke but can't source the electrical steel, not sure how critical this is for a DC choke. I have a spare welding transformer which is fair bit larger than a MOT that might be ok. I...

Hello, The choke is post-rectifier. The choke resists changes in current and hence smooths the output. Attached is a schematic from Google but it is very similar to what I'm doing (most old arc welder work in this way).

Hello, I want to make a choke for a AC to DC welder conversion. The welder is a 50hz single phase oil cooled unit with constant current output upto 110A. I will bridge rectify the output to give rectified AC output. I need to smooth the output and as I need a constant current output, I'll...

That kinda makes sense as you would lower angle of attack to keep the lift constant as velocity increases thus lowering the lift coefficient which would in turn lower the induced drag coefficient.

But CDi = (k*CL2)/ (pi*AR) (coefficent of induced drag) doesn't have a velocity term and neither does CL (coefficent of lift) so I don't see why it would change with velocity.

Induced drag of an airfoil should be inversely proportional to velocity^2 wiki states "Since induced drag is inversely proportional to the square of the airspeed" Ok but [Induced Drag = 0.5 * Density * Velocity2 * Wing Area * Induced Drag Coefficient] which is proportional to the veloicty^2 and...

Hi Is anyone aware of a circuit that could provide a phase shift independent of frequency? I have thought of doing it digitally but the number of components needed are ridicules. Thank you

Thank you both very much for your help. I understand it a lot better now.

I can see that it does seem work. However I thought that RMS using route 2 was for sine waves? Am i missing something? Thank you

Hi I have a question to do with using PWM If for example I had a 1ohm load and a voltage supply of 4JC-1, I would get a power draw of 16JS-1, now if I had a duty cycle of say 50% I should get an average power output of 8JS-1. However if i thought of it as having an average current of 2CS-1 and...

But if i double the voltage then the current should double at a set rpm? So if I had a 12v motor that at 3000rpm had a back emf of 5v and a current of say 20A if doubled the voltage the current should rise to 40A? To do this the net voltage needs to be double so at 24v the back emf needs to be...

I know that as rpm increases back emf increase and current drops which reduces the torque. So what I’m trying to work out is this: If I had a motor spinning at 3000rpm and had a load of 10NM a supply voltage of 12v and back emf of 5v. If I then doubled the voltage to say 24v and increased the...

Would i be right in thinking that back emf is indapendant from supply voltage and is just proportional to RPM?

If i have a series DC motor and at say X rpm it has a back emf of 11.5v and supply voltage of 12v and i increased the supply voltage (keeping rpm the same) would the back emf stay the same? and if not would the diffrence between back emf and supply increase? Thank you.

The motor draws 26Kw (under high load (what i tested water temp with) ) and can run at 18kw all day. It runs at 72v. I won't do it on the electric motor because the efficency is so low but may try a higher temp system for fun. Thank you very much for the help Mech_Engineer, stewartcs and...