ante

Hi boschman, Welcome to out forum. This is most likely a capacitor 100nF (0.1uF) and it has nothing to do with horseracing! ;)

Thanks AG, I’ll brows through it! Just a short comment at this stage; This is a local UK manufacturer unknown to me. I am familiar with some of the stuff manufactured by for ex. Zapi, Sevcon, General Electric, Cable Form, Curtis, Linde and Sigma to name a few. I did not expect to find any deep going presentation on how to construct a PWM circuit and this was immediately underlined, quote: “4QD manufacture PWM speed controllers for electric motors so you will hardly expect us to give you all our own unique circuitry and technical know-how” ;)

Hi AG, I couldn’t care less about the way a golf carts drive system is constructed! I know from experience how torque changes and how it’s possible to optimize it by changing the frequency of the PWM. There are even times when there is a substantial gain in changing the frequency within a certain range in proportion to the rpm to have maximum torque over a wider rpm range. But as far as I know only changing the pulse width is a proper way to control the rpm.

I agree; using this kind of non galvanic isolated device is suicidal! :o

Hi AG, If you like to improve the stability of the zener D8 it is possible to add a standard rectifier diode (i.e. 1N400X) in series (head on).

I don’t know where you live but this came up (and many more) on “prism+laser” in Google!: http://www.escoproducts.com/html/prisms.html

Thanks Tkjas! Have you tried it? Is it stable enough to get a reasonably good measurement?

Hi thoffen, Welcome to our forum. You could fit a prism to the shaft of a stepper motor and aim the laser at it. This stepper could then be fixated to another steppers shaft and you got X, Y and Z. Poor cat! ;D

If that did not help; this might: http://www.electronics-lab.com/forum/index.php?topic=5379.126 ;D

This might give you a clue:

Hi AG, That’s correct but; the torque does change long before this point (and thus the rpm under load) due to the inductance of the motor winding. When constructing a PWM controller for a motor there is some consideration regarding the frequency vs the inductance. This means that you need to know in which rpm range you are using the maximum torque when deciding the frequency. If you need to change the rpm without changing the pulse length it’s done by the amplitude.

I don’t really see a computer PSU as a DC-DC converter, more like an AC- DC converter or primary switched DC-supply. I believed computers where more sensitive than they obviously are since they seem to accept dirty (cheap) DC. I have seen many HiFi stereo amplifiers with only a pair of rectifiers and some electrolytic caps barley filtered at all and still no hum. In one resent case (a receiver 2X100W) which only had 2X2200uF on each side of zero, 55 Volts at standby and about 45 V - 4A at 80W output. I mean if they can get away with this it cannot be very critical!

Yes with the LM350

Do you think so; well it’s a complete PSU not just the pre-regulator! It isn’t a paper towel, it was my scanner set on color on a gray scale pic! ;D

I found it, this one worked very nicely:

OK, so you mean this : http://electronics-lab.com/projects/power/011/index.html That’s an interesting approach; I remember I have tried something similar once. I’ll see if I can find the schematic.

Where I live I can buy a computer PSU (450W) for less than $20US. As everyone knows they are multiple voltage PSUs very compact and light. It shouldn’t be difficult to produce say a 2 X 40V 2 X 8A for the same amount and with the same physical size. BTW. A 40V 40A unit is not a bench PSU it’s a welder! ;D

How about Q2s base? Just left open? How does this work?

Hi Zeppelin, The 100% load swing means that a current swing (in this case) 0 to 5A creates less than 10mV change in the output voltage and less than 5mA in the output current! Ripple at nominal load (in this case 5A) is +- 15mV RMS. Not bad, I’d say! ;)

Yes I know what you are getting at; it’s not the first time this discussion has been up! ;D Let’s do it your way; let’s change the resistor for a 120R and we’re really safe! ;)

Hi Paul, Welcome to our forum. The heatsink you need shouldn’t be inside the case anyway to be most effective! To help you more in detail we need the schematic to see what could be changed.

Maybe nobody has a clue what you are talking about!

Hi AG, Well, Gary built and tested it without any problems!

Hi Trigger, I have to disagree; when I was looking for a bench PSU I found that a linear one with the same data was twice as expensive as the one above!

Hi kebloks, Welcome to our forum! Looks good, try it!