New PT-1 to me seeking upgrade advise

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abril
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Re: New PT-1 to me seeking upgrade advise

Post by abril » 28 Dec 2015 12:26

My PT1 velleman supply which I no longer have.
10693

tim_bissell
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Re: New PT-1 to me seeking upgrade advise

Post by tim_bissell » 28 Dec 2015 18:21

I've never tried 9V PP3s as alkaline batteries drop to quickly from 9V for it to be worth it (IMO). I think a small 12V Sealed Lead-Acid battery with a charging circuit, fed into a 9V regulator would be a better approach.

I quite fancy the idea of trickle-charging the battery with a solar panel!

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 28 Dec 2015 18:53

just dispense with the regulator and use some 2ah 9.6v cordless drill battery's, at 300ma you should get a good 3hrs play time while the other one is charging. problem with trickle charge and use at same time is noise from the charging.

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Re: New PT-1 to me seeking upgrade advise

Post by tim_bissell » 28 Dec 2015 23:14

Ah, I should have known there was a reason for the complication in battery PSUs... I like your idea of the cordless battery drills, otherwise it would have to be an overcomplicated system with two batteries, a micro controller monitoring voltage and relays for alternating batteries states from 'charging' to 'driving'!

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 29 Dec 2015 04:52

from what i have read those new super regs like the one i posted earlier are lower noise than battery, problem with them is that they will run hot like all regs do if the input VAC is not closely matched to what is required on the output (shunt excess power as heat) they also dont like long runs of cable on the output so might be best to stick the supply and transformer in the same case as the supply circuitry or very close. i have two sitting on the bench waiting for custom transformers coming from Troidy for my Raspberry Pi and DAC+ which is connected to a diy headphone amp as a headless music player.

if your using one of AK's new motor supply already then i would not even use any other form of regulated supply (inc battery) unless he has supplied a wall wart for power in which case i would look into something better.

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Re: New PT-1 to me seeking upgrade advise

Post by PinkTrichard » 29 Dec 2015 08:16

I'm currently a stock pt1 (new bearing, achromat). We are on a pimping project, although we change our mind a lot, and are both too busy with other things really. K drive is a possibility. It is the holy grail to Arthur, but also a bit of a black box mystery. But I was impressed with the pp3,and like baldrick, have a cunning plan, which I might allow to distract me.

The lm317 is no slouch for voltage regulation. Just how much better is your new regulator? I am also thinking of tinkering with the power to the pips, if I can do it for modest cost, although poor old Owen will despair of me having patiently attempted to explain, with pictures, how the voltage reg at the input of each stage, and the transconductance design, mean any small ripple on the main rails vanishes to nothing. I only sort of understood...

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 29 Dec 2015 14:52

PinkTrichard wrote:
The lm317 is no slouch for voltage regulation. Just how much better is your new regulator?
not my regulator but one i have been recommended for its superb noise figures.

i dug this up on google http://www.edn.com/electrical-engineer- ... oise-floor the LM317 scores points as its adjustable via a pot but if you need a fixed voltage then the fixed regulators are the one you need unless you can measure the voltage out of the LM317. i'm by no means an electronics engineer though. linear voltage regulators are just to replace the wall wart pack with something better not as a replacement for the motor electronics in which case you might be better with an adjustable voltage regulator such as the LM317.

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Re: New PT-1 to me seeking upgrade advise

Post by PinkTrichard » 29 Dec 2015 16:41

Thanks again. I do like this forum. I did a bit of research myself, and whilst the LM317 is good, the ripple voltage of the TI regulator is in a league apart. It's not hard to measure the voltage out of the LM317 but I am intrigued to try the TI (if I could work out what to do with that aluminium block???). Just a couple of points I sort of know a bit about
"Wall wart" refers to a power supply in a plug box, and usually, especially when said in the perjorative way , refers to a fairly cheap simple and noisy SMPS power supply. In fact, the device supplied with my PT is not an SMPS "wall wart" but a regulated linear device that happens to be in a similar package. So just using another identical linear regulated supply in a separate posher looking box wouldnt help. However, I don't think the voltage regulation used is even as good as an LM317, and the power output is limited to 300mw. So there is some (potential, theoretical) benefit to a better linear supply. Or a battery. The cunning plan is to build a regulated supply with an input which is switchable between an internal 12v transformer, and an external 12v battery supply of the laptop battery type. When I have time...

I am not (yet) looking to improve the "motor electronics" - just feed them with a more stable power source, having been impressed with the PP3. I'm not sure how much more improvement is needed to the motor electronics of the PT1 board. It doesn't drift with the original motor that I have noted and so the servo loop appears more than fit for purpose.

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 29 Dec 2015 21:36

the alloy block is to shunt heat away from the regulator which is why the regulator board need to be placed in a small metal box (forgot to say this). the more voltage you feed into the regulator the hotter it will get so you need careful matching of the transformer. lets say you need 9vdc then you would need an 11vac transformer as the rectifier and regulation have a voltage drop (how much voltage they consume by themselves). if you feed a higher voltage into any regulator then it will run hotter so to run it as cool as possible and extend its life you match the required input voltage as close as you can to the output voltage taking into account the voltage drop of the rectifier diodes and the regulator.

yes a 'wall wart' is just the thing you plug into a wall socket that usually supply's a DC output. if AK is using 300ma ones then its a sure bet that the whole motor control and motor is consuming less that that. if so there are other solid state regulation available that are used for headphone amps to give one example.

so to give a quick and dirty, if the 'wall wart' you are already using states its 9VDC output then use a 9VDC regulator with a good quality 11VAC transformer to replace the 'wall wart'. if you use any form of higher voltage as the input then expect more heat from the regulator. one other thing is if you use a DC supply to the regulator then you would dispense and bridge the rectification diodes and drop the input DC voltage by 1VDC so a 9VDC output will need a 10VDC input. so why would i be talking about supplying a regulator with DC, simple answer is its cheating to get better cleaner regulation from a cheep 'wall wart' instead of using an AC transformer.

BTW i'm still learning and its so far my findings.

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Re: New PT-1 to me seeking upgrade advise

Post by PinkTrichard » 30 Dec 2015 07:25

Hmm. I realise the aluminium block is a heatsink, but from the product photo it is not apparent how it connects to that tiny ic. Maybe it's more apparent in the flesh.

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 30 Dec 2015 12:58

it sits under the IC instead of over it and is held in place when using the mounting spacers. there is a small 'pad' under the IC on the board to help shunt the heat towards the aluminium block.

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Re: New PT-1 to me seeking upgrade advise

Post by PinkTrichard » 30 Dec 2015 15:55

Thanks. I've found (and ordered) another variant which is a complete kit, and uses a more conventional heatsink on the chip. I am hoping that it can dissipate the heat from 12v down to 9v - since 12v is a readily available value in both DC batteries and mains transformers.

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Re: New PT-1 to me seeking upgrade advise

Post by backtotheblack » 30 Dec 2015 16:43

excellent. just a little word of caution. make sure that the heatsink is not stuck on with double sided tape as that is about as much use as a chocolate fire poker.

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Re: New PT-1 to me seeking upgrade advise

Post by PinkTrichard » 30 Dec 2015 20:37

backtotheblack wrote:excellent. just a little word of caution. make sure that the heatsink is not stuck on with double sided tape as that is about as much use as a chocolate fire poker.
It's a kit. Heatsink paste is in a sachet, but I have a small tube. Just wondering if the case needs ventilation. I'll wait till the bits arrive

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Re: New PT-1 to me seeking upgrade advise

Post by thezenroom » 10 Mar 2019 20:54

OK, I know I'm raising this thread from the dead, but I want to add my two penn'orth on power supplies for the PT1.

Firstly bigger is not necessarily better. The larger a transformer the more noise it adds to the output current. So yes to some headroom, but 50% is all thats needed. Second the LM317 also adds noise - best avoided.

For a budget upgrade I'd buy a RAAD wallwart, its a 9 volt regulated linear PS designed by RAAD for their guitar effects-peddles because they couldn't find any off the shelf items smooth/quiet enough. The 500mA version is the one I'd plump for, but they do a 700mA version also (£17).

If you are going to build a diy PS then you can buy a top quality voltage regulation board already populated here for $59:

https://www.teddypardo.com/diy/buy.html

Explanation of design philosophy of the circuit here: https://www.teddypardo.com/diy/superteddyreg.html