In message snipped-for-privacy@4ax.com, T i m snipped-for-privacy@spaced.me.uk> writes
For my fairly basic use, I just leave both the fine controls and the amps at maximum, and use the coarse volts knob for control. The huge advantage is the digital readout which shows both volts and amps simultaneously, which is important for older motors. Just one example is pre war permanent magnet motors. The magnets tend to degrade over time, and consume more and more amps for the same performance, which leads to overheating and damage to motor windings. Watching amps consumed, and knowing the usual usage, is therefore important.
Ah, that makes sense for the current (compared with leaving the fine current control in the middle), as it's a 'upper limit' and assuming you may need the full output etc.
Understood. That said, if I was doing that same job with my Weir PSU's with a single meter is I would set the voltage to something suitable, say 12V and then switch it over to current and could then watch the meter.
Only if I reached full current would the voltage drop.
Ahh.
Understood. I was doing the exact same thing when testing the Arduino based MR automated project with BIL [1].
We were both amazed at the differences in current pulled by his older and newer locos.
Because there was no speed feedback in the project and the vast range of speeds resulting from said motor efficiencies, rather than going for the choice of running 'any' of his numerous locos, we selected a sub-set that all had similar power requirements.
I can't think of any role where the noise from the PSU would be an issue to me or the controls too coarse. (And I have used what looks outwardly to be an identical model for a range of power and electronic things and found it fine).
Cheers, T i m
[1] I actually still have our MR automation test rig here. 4m of straight track with a bypass section in the middle. 4 digital IR reflective sensors positioned by the track near the ends and a diode connected 'dead' section each end of the track to prevent overruns.
Loco, pulls away from end (with inertia) to max speed (adjustable with pot) to the 1st remote sensor then slows (with inertia) to a creep speed to the second sensor when it stops.
The two points are set (using bridge drivers and a cap) and loco drives back the other way and round the bypass and back onto the main line, to the remote sensors. And it actually works. ;-)
Well when you say they are dead, its probably just capacitors, unless they have been abused of course. My main problem with modern supplies are that they are switch mode. Firstly unless very well designed they produce massis of interference both down the mains, and radiating, and often there is a residue actual on the DC as well. I'd be tempted to visit somewhere who sells to Ham radio people, like Martin Lynch or Radioworld, or there are several others, as they are more likely to know of gotchas on individual supplies than than your average Ebay cheap Chinese box shifter. Brian
I think one is still working but not to full spec (it's been a while since I've used it / them).
Ok, not sure that would affect a battery or model train. ;-)
But may well be more expensive.? ;-(
I still have my 10A 13.8V linear 'Shack' PSU, a smaller adjustable SMPSU 5-15V, 0-15A (current limiting) RC usage PSU and in the loft, a
*very* big and heavy 10A bench PSU that died (can't remember the voltage range).
It's just that apart from the RC supply, none of the others are working fully and whilst I can charge 12V batteries with the RC PSU, it would have been handy to have 24V's worth of battery charging (mobility scooters) and even higher voltages for a two wheeler scooter.
Just knobs. ;-) Four which work independently when the two PS are seperate, or just two of them when ganged.
It seems to do everything I want and hasn't annoyed me in any way. Which is saying something.
I'm sure a SMPS one could be smaller, but I've built mine in on the side of the workbench, so not taking up usable space. A bench top one would get in the way at one point or another.
I did not choose a linear power supply for any particular reason but as I said the current limiting was more important for re-charging Ni-Cad batteries in a couple of tools I have. Their chargers having died a few years ago.
Both voltage and current setting are achieved using an encoder. When you press the knob in the range digit flashes and whilst it remains in that mode turning the knob adjusts the displayed value up or down.
Say you repeatedly pressed to set the 10mV range you can adjust the voltage up or down throughout the output range 0 to 30 volts. It does take quite a few revolutions to get the output up to 30volts from zero though.
OOI, don't most bench chargers have adjustable current limit?
Like they do. ;-(
Understood.
Ah, that's interesting and thanks for the clarification.
So if you set it on the units field you could wind it down from say 12 to 5 volts just by turning the knob (eg, it wouldn't just go from 12 to 10 and up to 19 and back down etc)?
If that was the case and based on the fact that most people would set the volts in 'whole unit' increments, that would make it much more useable IMHO).
Similar thing could happen with the current limit in that you could have it on the .1 range and still have reasonable speed and granularity?
Do you have to leave it to 'time out' on the individual digit for the above to happen (eg, to stop it just cycling round that field or does it never do that)?
The display would go from the initial 12, 11, 10, 9, 8, 7, 6, then 5. Conversely going up 12, 13, 14,.....up to 30.
Yes and obviously on the 1 amp setting you only have five steps and on the
100mA setting 50steps.
Yes you have to leave it to time out but it is only for 4-5 seconds.
The output display when setting mode increments/decrements the whole of the voltage or current display.
So in your example when in the 100mV field, turning the control anti-clockwise the display would show 11.90, then 11.80 and so on down to
5.10 then 5.00. Left for 5 seconds the display stops flashing and the output is now set at
5.00 volts.
The display does not cycle round. When at the minimum or maximum is gives a bleep as a warning. The control can still be turned being but an encoder does not change the output.
Is there any prior indication on what field you will be on when you press the encoder again John or is it 'suck it and see' (press it and see what flashes)?
Check.
Ah, so, what happens to the output voltage between selections? Does it stay at the last setting, follow the changes or disconnect till the new voltage is selected etc?
Noted (and that might be just as well, depending on the output status during changes etc).
No. I have just tested that and from power on the most significant field flashes in either voltage or current setting mode. The least significant field is only four quick pushes away.
If you miss it, just keep pressing as the display cycles through most to least field and then back again least to most field, which seems a bit wierd to me!
I have never given this a thought as it seemed to be intuitive to just repeatedly press the control to get to the one needed.
Erm, so with current that would equate to whole amps and with voltage,
10's of volts or just volt units (given it goes to 30V)?
So that would be from 10's of volts?
And me ...?
Yeah, I'm sure if it was in front of me I'd work it out easily but I'm trying to ascertain how time consuming it might be if you were changing stuff regularly and didn't need the accuracy / granularity.
So can I check on this please John. From power on, both voltage and current flash the MSB and assuming you do nothing, will stop flashing in ~5 seconds and will return to the last used values I understand (say 12.000V, (or would it be only 12.00V?) and 3.000A current limit) ...
... (Recap) If you then turn either knob then you will change values in 10's of volts (or just volts?) and whole amps?
If you want to then say set it to 5.004V (for some reason <g>) you first (just) turn the voltage knob (because it defaults to units?) anticlock till it reads 5 in the units field then press the knob three times and then ... (while it's still flashing or otherwise) turn it to
When switched on the displays show the last settings of voltage and current, after 5 seconds the displays indicate the measureded load requirements.
Yes
It does seem a little complicated but within a few minutes it will become obvious as to the setting up.
No. The displays show the last settings used and then revert to the measured values. To change them you press the relevant control and set your requirement.
Yes but only after you have pressed the control knob.
You cannot set it to 05.004V
To set it to 5.04V - it only has a 4 digit display so can only get to 10mV Power on Press the voltage control knob The 10V digit will flash - Turn down to zero Press the voltage control knob again. the unity volts flash Rotate control up/down to set 5V Press control knob twice to get to 10mV and rotate to set to 05.04V
Isn't that what I said or were you not saying no to that bit?
Which in case of the voltage and assuming it's not already current limiting will be the same as the initial value and the current will be the actually current being drawn (not the limit)? But the point was it
*will* be the last uses values, not some arbitrary values.
Yes, I get that bit. ;-)
Eh? So the knobs don't work 'normally', only when in setting mode?
Turn on. Display shows last used settings with the MSB flashing. Allow 10 seconds. Display show last voltage used and current amps drawn. Turn either knob and you do or don't change the values 'live' John?
I wasn't sure if you regained that extra digit when only showing single volts rather than 10's of volts. Ok, that makes it clearer.
Yes, that's sorta how I thought it worked, but I am now confused re where you were saying that if you turn the voltage knob up or down either side of 10V you will see 10, 9, 8, 9, 10, 11,12 etc?
Let's try a recap (I will get this pinned down). ;-)
1) Switch on
2a) At switch on and for ~5 seconds ... display shows last used voltage and current limit values with the most significant field(s) flashing. So if it was set to 12.00V and 3.000A CL, the 1 (of the 12) and 3 are flashing. (I think I understand it to be this)
or
2b) At switch on and for ~5 seconds ... display shows last used voltage and current limit values with the most significant field(s) flashing. So if it was set to 12.00V and 3.000A CL, the 12 and 3 are flashing. (not this?).
3) Leave for ~5 s and the PSU will provide the volts and current limit values displayed.
4) Press the voltage button once and because it defaults to the first (most significant) digit, that will flash, allowing you to set that field ONLY. eg, if you keep rotating it clockwise from 1 it will go to
2 then 3 (then stop doing anything as the max voltage is 30 (and I think you said it will beep)). Whilst it's still flashing, turning it anticlock will see the display going from 3, 2, 1 to 0 and another 'end of range' beep. Leave the knob for ~5s and that digit will stop flashing and that value will become the used value.
5) If you press the voltage knob again (once it's returned to steady) you will 'still' be at the most significant field (so say the 1 of
12V) so you will be in the same position as in 4).
6) If whilst the display is flashing, you press the knob a second time, the next (less significant) field will start to flash, so if it was reading 12V, it will now be the 2. Then rotating the knob clockwise will see the values going up to 9 (then beep ... or only beep once you try to go *past* 9?) and anticlockwise the value going back down to 0 (and then beep there or if you try to go past 0).
7) With the active voltage adjust units field left as the active one (so 2 of 12V), and ~5s have passed, rotating the voltage knob will increase or decrease the voltage in whole units up to 30 and down to zero. (?)
8) With the display flashing, repeatedly pressing the knob will see the flashing field move backwards and forwards between the two ends (like ''Kit' the car on Night Rider). ;-)
Assuming I'm close now, I'm also interested to know at what point the voltage (/ current) actually changes? eg, is it as you select it or only when it's set?
Also to confirm the knobs *can* be used live as I believe you have said previously across the full range and in whatever increments you have last set (1V, 0.1V, 0.00A etc).
When powered up both displays show the users last settings but do not flash. After a few seconds they display the supplied values. CV led lit assuming not in current limit mode.
This is correct it will be the last user set values. I do not know how long it retains these values as I have never left it powered off more than few days.
No problem you got me to try something I had never given a thought about i.e. the digit cycling. Hope this has been of help.
Oops missed this one Yes you can turn the knobs until the cows come home and it will not change anything. Only when the knob is pressed in and a digit is flashing. I presume pressing the knob signals the control circuit and enables the knob encoder to change something.
Yes, probably good if you were to nudge them round by mistake. [1]
Cheers, T i m
[1] Years ago I was having the physiotherapy on my back for a trapped nerve and had a session of electro therapy, electrodes suck on my back and hooked up to a machine causing my back muscles to contract and release at a couple of second intervals.
Laying on my front, machine on a trolley by my head hands and me on my elbows, left to 'turn the voltage level up, as / when you can handle it' .. .
She left me set on level 3 of 10 and I'd slowly got it up up about 5 when, as I'd just got my hand on the level knob my elbow slipped off the end of the bed and I span it round to 10!
Now, whilst I could just about cope with the pain, I initially couldn't recover enough between bursts to get my hands back on the machine to turn it down (but after a few goes I did). Now, if you had to press the knob in fist, that wouldn't have happened. ;-(
Would have thought this should have been a stepped switch to prevent just this. I take you survived this misfortune and are now worse for it. I felt for you when I read your recollection.
I had to endure a bout of Physio terrorism and did ask to see their big book of 1001 Ways To Inflict Pain (available in hardback)... Ha Ha only joking
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.