PTS Flowbench Forum

Ok thanks Tony, as always a great help

One thing about multi turn potentiometers.

One option you don't see very often these days are what are called "vernier drives".
These are a friction ball drive arrangement, that usually have a reduction ratio of 6:1

The knob fits onto the projecting 1/4 inch shaft, and on the other end is a 1/4 inch female socket and locking screw into which the potentiometer shaft fits.
The two outer projecting forks are usually fixed to a front panel to prevent rotation and support the knob.
The friction drive is very smooth without any slop or backlsh.
Rotation is continuous, there are no end stops.

Six turns of the knob then turn the potentiometer shaft one turn.
These are fun to play with, it will turn a standard 300 degree rotation potentiometer into a five turn potentiometer.
It could also turn a ten turn potentiometer into a 60 turn potentiometer !!

Google "vernier drive"
These often appear on e-bay and they are not expensive.

Seriously though Tony, how do you remember all this? Do you forget your kids birthdays like me, but can recite the bore stroke and capacity of any domestic engine?.
Those drives are very cool, I can think of a couple of uses.
Checking eBay now

Jim

RACEPUMPER wrote:Seriously though Tony, how do you remember all this?

Being a little bit crazy helps.

did anyone ever make this work? I have some of those SSR from another project.
Mike

Go looking for the other post Mike, someone else has had one working. The other post is called adjustable scr I think

Jim

I tested the one from eBay on my flowbench maybe a year ago. The POT is less than a 360 rotation more like 270 if I recall, it is very ratchety. I ordered some sample pots from my electronic supplier to see if a better quality pot would make a big difference, I have not tried them out yet. The sample pot also comes with a 1/4" shaft so I can use the knob I supply with my SSR setup which is larger in diameter. The pot that comes with the eBay one uses a knurled shaft and has a small knob.

The larger diameter knob allows a finer adjustment I have found. You will also need a heat sink as discussed previously.

The SSR's without the control module will not work with the PTS PID control.

If you have SSR's other than what we are discussing with just the pot control, keep in mind you need "random fire" style with the phase angle control module.

I have a 10 turn 500K pot I will give it a try and see what happens . I have a couple heat sinks but they might be to small long term hopefully this will get me going for the short term

This setup would be my second choice for a control over the PTS SSR I supply.

I had no issues the short time I ran it on my bench for try-out. I would go this route over the HF router control on a budget build as it gives you all motor control due to the higher amp load capacity so, you can control all your motors and not limit yourself to 1-2 motors on the control. This also does away with having to use check valves on the non-controlled motors which would be one less thing you have to source or build. The overall cost would be almost equal.

I have given some thought to actually supplying this setup with the upgrades I mentioned but till I would do it and add some $$'s to make a small profit it would probably not be worth my while to tie up the cash to keep them in stock other than if someone "wants one right now" I would have them available.

In My kemo ssr is possibile to use two potentiometer For each ssr.
one make a large regulation of voltage,the other is for fine regulation of motors speed.
tha relais can use without heat sink,but I install it on a large 3mm aluminum plate. And this relays is capable to handle 3 motors,but to make low the temperature,I use one relais for each couple of motors. Soon new pics on my topic.