Recommendations - Model Train Controller

[mister_e]

Unfortunately i don't have anything like that here to test, but Maybe the PWM have to be smooth first...

what happen if you place a big capacitor (470 & up) in parallel with the motors?

What happen if you place a capacitor (few uF) on the mosfet gate pin? (transistor base)

What happen if you use a variable voltage regulator (or PSU)? instead of PWM?

[malc-c]

Unfortunately i don't have anything like that here to test, but Maybe the PWM have to be smooth first...

what happen if you place a big capacitor (470 & up) in parallel with the motors?

Tried both high (1000uf) and low (100uf) - the loco won't move

What happen if you place a capacitor (few uF) on the mosfet gate pin? (transistor base)

Tried, 1uf to 10uf. with a 1uf the growling was less noticable, but the slow speed control became less. Increasing this to 10uf and the loco had almost no ability to crawl.

What happen if you use a variable voltage regulator (or PSU)? instead of PWM?

Don't know as I don't have a varible regulator to hand.. what would be the advantage of using one over using a pot accross the supply with the wiper connected to the base of the NPN tranny ?

[mister_e]

what's your actual schematic?

how much current your motor need?

[malc-c]

Typically these loco's draw around 300mA - 600mA ( a quick test showed mine drawing 380mA with no coaches at full throttle )

The schematic as it stands is attchaed

[Darrel Taylor]

Saw the video.

I've seen snails move faster than that, when it's raining.

Cool.

Hope someone can figure out the Growl.

[malc-c]

Saw the video.

I've seen snails move faster than that, when it's raining.

Cool.

Hope someone can figure out the Growl.

LOL - thanks !

I'm not too bothered about the noise the PWM makes, but as this will be used on a club lauout, other members might complain...

[Acetronics2]

Typically these loco's draw around 300mA - 600mA ( a quick test showed mine drawing 380mA with no coaches at full throttle )

The schematic as it stands is attchaed

Hi, Malc,

R3 is no use at all here ... short it !!!

... but a 1N 540x cathode at the + 12v, anode on the V+ output could be rather useful ...

Alain

PS ... for Growling, may be you could try to " unsharpen" the PWM to somewhat with increased rise and fall time ... by inserting a filtering coil in series in the output line ( a LITTLE smoothing capacitor too ??? )

[malc-c]

Hi,

Don't have that Diode suggested, have plenty of 1N4148's or 1N4001 to hand, would they do ?

[Acetronics2]

The 4001 will be a bit too weak ... for serious use.

try to find a 3A rated model ... or use a PNP Darlington with diode Built in !!! like BD678/680

Alain

[Archangel]

Tried both high (1000uf) and low (100uf) - the loco won't move
Tried, 1uf to 10uf. with a 1uf the growling was less noticable, but the slow speed control became less. Increasing this to 10uf and the loco had almost no ability to crawl.

4 - 8 kc whine? have you tried going even smaller? say .1 or .01 uf ? There is an outside chance you are not hearing the direct frequency in those motor coils but rather a beat frequency from the difference between 2 frequencies in which case you may be looking at bypassing RF.<br> I would bypass the motor from each power lead to the case too.

[malc-c]

Thanks for the suggestion, a tad over my head, but I think I follow your drift.

Darrel / Steve,
I've noticed that if I advance the pot fully (thus taking the A/D input pin to supply) and then turn it back down the loco stays at full speed, and the only way to correct this is to disconecct and reconnect the supply. - any suggestions (could this be down to the wrong setting for ANSEL)