I know Inskip Sctc, or as it was Hms nightjar, it then became a Vlf receiver, now supposedly a cadet centre, you can see the lights from my house and work, its only 2 miles away.
I think maybe its time to try a prototype, there are many variables testing it out will tell you a lot, maybe you could do a lash up on breadboard.
Or was it the Black Bull and White Bull............?The White Horse,The Black Horse and again one who's name I can't remember.
All still there, the derby arms at inskip which recently has opened a chippy in the old toilet block, the white and black horse are still at Gt Ec, 'tother one is long one I think it burnt down.
Yep I htink a zener would be a good idea, put a 10u electro across it to damp the noise, voltage will be fairly constant, it will change as the supply varies but only by a 100 mV or so, probably not enough to notice, you could put a current source above the pot if it was an issue.
I see no significant issue. It's basically just a diode OR function between the two voltages.Ok, But the motor voltage is full wave rectified but not smoothed dc. To superimpose or swamp a pulsed voltage surely would be problamatical?
Not the way I conceive it.But again if you are suggesting as I think, that this pulseed voltage is applied additionaly to the motor drive voltage then again I have to suggest that resolution of the motor control would be reduced no? I would have to turn up the pot to a level which overcomes the onboard diode network before any movement occurs.
The auxiliary circuits would have a diode bridge to rectify the pulses and/or the motor voltage to generate the DC for those circuits.
The motor would be directly connected to the track with no diodes, so its resolution would not be affected.
Or am I misunderstanding how the train motor works?
I was thinking of short pulses, perhaps 0.1ms or so at perhaps a kHz, where the motor inductance would block any significant current from the pulses.You suggest that the additional supply for the onboard loco auxilaries is 'mixed/superimposed/riding etc' the track voltage for the dc motor. With the dc motor connected directly to the track without blocking diodes as you suggest, it would still present a resistive load to the aux supply being in parrellel with the diode bridge no? Also you do not mention what type of pulses, freq and duty cycle.
In you schematic that is done by a DPDT switch which would switch both signals.We should not forget that to change the direction of the motor and hence loco we change the polarity of the dc via the dp switch on the output. We would also have to do this with any additional aux supply voltage.
Yes.'If it a'int broke don't fix it'..............well thats what I think but am open to ideas.
Yep that current source looks ok to me, take note of the 400mw max dissipation, calc the voltage across the device then x by 10ma.
Funny I've talked to a few train enthusiasts that dont like the idea of pwm, its a very popular technique, I've never heard the demagnetization thing before, if the motor is protected from back emf I wouldnt expect with modern neo magnets for that to happen, maybe with old motors with alnico magnets it could be possible for the coils to generate a stronger reversed field than the magnets.
If you dont want pwm you have 2 options, the way your going or to use current control with feedback, the latter is impractical with rails so you might be on the right lines the way you are.
I have messed with scalextric, and yes I built a controller using a processor, the motors are controlled via pwm, I found that the characteristics of cars changed, for the better, newer mabuchi motors on dc tend to do nothing with increasing voltage then suddenly take off almost uncontrollably, whereas with pwm control is much better, part throttle cornering is possible and you can easily make cars crawl along the track, noise is the only thing, the cars sound a bit like my dewalt cordless drill.
...... noise is the only thing, the cars sound a bit like my dewalt cordless drill.
Sorry mate. Just noticed it's gone seven and corrie's on!............... better than watching pants on telly though.
Its not so much the telly, more the adverts.
I wish I didnt have to get up at 5 and go and attend with a load of zero watt bulbs run an alcoholic maniac.
With the resistance values you have the lm344 ought to be fine.
Its welcome.The following is constructive criticism:
With the resistance values you have the lm344 ought to be fine.
Pwm is easily controlled by digital methods, however it also benefits from high torque & efficiency (the latter in the controller).
The following is constructive criticism:
I dont argue with the demag situation with pwm, however theres a couple of things I'd have to argue with you mentioned, instantaneous power running a 6v motor at 50% from a 12v source would be quadruple the motors ratings yes, however average power would be similar to what the motor would be at 100% on 6v power, and heating would also be similar, possibly less as for the first part of the pwm pulse the inducatnce of the motor would create a current ramp starting low down further reducing average power.
If you tested a motor and it did run warmer on Pwm then I'd have to say its something to do with lc resonance from the higher voltage or posibly dumping energy into a flyback diode or snubber, or switching transients both from electronic commutation and the motors commutation, one thing Pwm does demand is good filtering on the motor side to prevent arcing of the brushes or oscillations at the switching fet.
Magnetic field loss as I understand it starts to happen around the curie point which is hot, over 200 degrees, unless it has a lesser effect lower down.
I wonder if either Pwm has earned a bad rep with model trains due to poor setup (manufacturers of controllers wouldnt have any control over the loco installation) or the track layout worsening some of the above.
Closed loop will compensate for voltage controls lesser torque, your only issue would be getting shut of the heat from a linear reg, how are you going to get feedback?
Some 'people' I work with are when it comes to brightness zero watts, and the gaffer is a maniac boozer who's very good at amateur dramatics. OH DEAR!!
LM334 not LM344, now I have Alzheimers,
You can still spell the word? Your one of the lucky ones! We shouldn't take the **** though.
..........sorry I meant a current source LM334, the idea is to keep current through the chain constant, and because voltage is dependant on current the voltage would also be constant which is the aim.
But the voltage on the Zener is constant irrespective of current? But I do see where you are coming from.
Pwm is the amount of energy over time, so if you push at a rate of 2 for only half the time, your actual push rate would be 1.
Also if you turn a 100w bulb on for a second then off for a second, if you measured the power used over a minute it would be 50w.
If you pulse something like a motor at a high rate you dont notice the on & offs it all blends into one reduced 'push'.
With respect appreciate all this.
Yes noise is perfectly good argument and a good enough reason to stick with Dc, I have a clock made from a decca navigator display, I've made a few clocks from old aircraft instruments, anyway its a 3 pahse motor, I drove that from an arduino usign Pwm to make 3 phases, it was noisy, but I managed to overcome that by shifting the Pwm frequemcy up to supersonic, however this might not be a good idea with motors using brushes, as the Pwm commutation might be higher than the motors own commutation.
Noise would have to be snubbed both in the loco and at the power source, 3 caps would probably do the trick.
Yes manufacturers are at the mercy of hobbyists with Pwm, they might say use use a snubber or else, but that doesnt mean to say that the customer will, and if the motor burns out they get a bad name.
A lot of railway modellers 'operate' their ' layouts' with pwm. Operate = Play, Layouts = Trainsets!
It is widely used. But as I said mechanical noise is the issue for me. Arguably I believe a controller of the type I wish to use is more smoother in operation. But just my own preference.
Your speed control is straight forward Dc, well I'm sure if you search google you'll find a Dc voltage to midi note converter, possibly with timbre or whatever you call it when you hit a piano key ahrder, so you'll be able to change the frequency of the 'engine' and its volume, if you go the arduino route assuming you can find something you dont even need a programmer, its built in.
This side sorted. Midi input/output usb modules (Pic ) are easily and cheaply available. Do not use voltage to midi note convertor as it is my preference to keep DC Track voltage isolated from 5v TTL and USB , PC. With ref to timbre u mean velocity. Now if you need anyhelp with midi I am your man!
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?