PISTON TANK DRIVE BOARD

Hi David
Do the engel boards still use relays ???

Yes they do. They are the orange boxes in their photos. They are fairly small but it does make it all a bit "clunky". It maybe also makes the unit a little slow but then I'm not sure that you need a high speed piston tank anyway.

We also know to our cost that MOSFET H bridges need to be specified correctly!
Thanks are due to John for suggesting the "fixes for the glitches" on the H bridge driver chip on the AMS board.

But, all in all, the Engel controller looks pretty good.

I think where the "AMS Board" can be useful is its flexibility for the enthusiast. Changing the PIC and a few connections means that you can go from a Piston Tank controller to a pump in and pump out controller with a connection to an on/off servo valve. The board is also flatter and maybe easier to fit in in most cylinders.

David

HI David
Have been playing around with new pics that you sent me with new soft ware on was running drive board on 540 size motor had it working on 6V was working fine didn't take the voltage any lower as i though i was asking for trouble on gates of fets, brought the voltage up to 15VOLTS and still seemed to work fine tried all sorts of things and could not get it to blow the board up have been really trying hard to kill it but it is still alive. But i wonted to see what would happen if Voltage to H bridge drive chip goes high because of back EMF from motor this seemed to kill the chip DEAD need to look at some form of crow bar protection across power rails on chip. But this would not have happend in normal running of the controller board
John

Hi John,

Glad to hear that the new PICs and the board are proving to be hard to kill - certainly what is needed.

Can you give more info about the connections you made to actually "brick it"?

David

Just an update on this topic.

I've now been running (and diving) my Resurgam at Barrow with the newly constructed, aluminium piston tank. All working nicely with the H bridge board on 12v (I added the extra capacitors and diodes, as discussed previously.)

Dave reports that the Engel proportional controller is also now working well. (It was difficult to set up initially.) He confirms that the response is a little slow. Use of relays??

David

HI Davy
Have been looking at making a digital proportional piston tank unit as you are quite aware the hard bit from the electronics point of view is how do you get some sort of linear out put from the piston traveling up and down 300mm of say thread, have sat thinking all sorts of ways on how to do it but have just come across some company that makes feed back pots, that can work linear up to 2meters long. I am waiting to get some feed back from the company as this would be the ideal way to go about being able to make the tank digital proportional of course what this means is the tank will work the same way as a servo,you won't have to worry about any encoding discs or magnets on the end of the shaft. If this works out should be very interesting as it will be a very controlable piston tank once you do this it will open up many ideas, that can be built in to the in side of the sub will have to see how it goes the electronic side of it should not be a problem as it is pretty straight forward what would be servo amp can now be done with soft ware so won't have to worry about saucing servo amps ICs which can be a pain in the neck.
John

david f wrote:Just to let everyone know that we are still actively working on this one.

Any more expressions of interest for?

- Bare printed circuit board (About £10)
- Assembled and tested boards.(£40 - 50)

David

Hello David,
as I'm a newbie to this Forum and catching up on what has passed, are these boards for d-i-yers still available please as I often 'enjoy' the surprise of seeing something that I've soldered together actually working! Though as a gears and hydraulics man I do resort to the use of the hammer when there is no result at all!
Regards,
Trevor

Hi Trevor,

Yes the project is still going on. I have just finished the first of a batch of 6 boards which I am making for my own use to a slightly revised design (as a result of Nigel and John's experiences) and this first one is working fine on 12v.

The PIC chip is still available from the AMS and I am only too pleased to share the board design/layout etc.

Where we seem to be having a problem is getting anyone to make boards and/or finished boards at a reasonable price for the AMS.

For most people it is still much easier and only marginally more expensive to get controllers from Engel.

So for enthusiasts only, wth a fair degree of skill, I would say. Apply within!

David

Hi David,
thanks for the reply, I have seen the ready built item from Engle but because I intend constructing my own dive system/ballast tank would prefer that to include the electronics component/controls as well. I should be able to make the pc board okay and can solder passibly, where and to whom do I send glittering coin'o'the realm for the design/component list and the chip[s]? This will give me something to do whilst awaiting my hull to arrive,

Trevor

Hi Trevor,

No problem. The chips are still £5. Have a look at the for sale section in this forum for the details.

(You do need to be an AMS member to do this. The current annual subscription is £12. There is a membership form for download on the main website or contact me at:amstreasure@googlemail.com)

Many thanks for your interest!

David

Well I did try to put him off, Richard!

But Trevor, you may wish to join this happy band of nutcases. (Richard included!)

David

david f wrote:Well I did try to put him off, Richard!

But Trevor, you may wish to join this happy band of nutcases. (Richard included!)

David

err, already aboard and the Coxsn's got my shillings!

Trevor

Hi David,
I must have missed that part of the For Sale when I was looking for 'how to buy' Anyway have written cheque for a couple of items, this will be posted in the morning. I cannot/did not see the circuit so I guess that you send this as a pdf attachment to enable laser printing to a photoresist foil or toner transfer methods,

Regards,
Trevor

Hi Trevor,

Sorry I did not identify you as member. I have been down in the South of England, without any membership records.

I can send you a pdf file for the board in the next few days but anything more detailed will take a week or two to put together - the wire links on the board need particular care but you could start to make the pcb.

I can't offer to give you too much support in getting the board working (We are only amateurs after all) but the H bridge board design etc, was published a year or two ago in the magazine and would be good background reading in the meantime. The same board can be used for pump or piston systems by the way, with a different chip.

Again thanks for the interest.

David

Hi David,
gracious! the Deep South that's a long way from home. No worry/hurry about the actual hardware as you say there's the board to make first and I haven't done one for a century or two so it'll be back up the learning curve for me and ther just might be a " oh bother!" moment or two!!
Trevor

Hi Trevor,

Thanks for your understanding - Henley on Thames it was!

You would do me a favour if you sent me an email (to amstreasure@googlemail.com) to remind me to send you the pdf.

All the best!

David

I didn't realise that you lived in that neck of the woods. So much flooding at the moment from the Thames. You could almost sail from your front door!

David

Hi Trevor,

Many thanks for your cheque for £25 to the AMS.

I am just about to send you the instructions and drawings by email attachment. Could I ask that you look at these over as a draft and let me know of anything which could be clearer/ improved etc?

A bit of collaboration would help us all. Many thanks in advance.

David

Hi David,
thanks for the attachment I have downloaded it and have skimmed through briefly, but will read over the next couple of days ,
Trevor

Hi Trevor,

Just to let you know that I have posted your PICs and a 12v air pump today, 2nd class.

I have also included a 12v solenoid valve and some of the bags from the original Rover car seat arrangement which I hope will be useful to you.

David

Good Evening David,
thanks for the heads-up on these items, I'll confirm the delivery when they arrive. Sorry about the slow response but I have only just thawed out after a long afternoo/evening in a freezing workshop rebuilding my lathe[ having stripped out the old heating system and not yet installed the new one having no intention of being in the shop in January!]. I am still ploughing my way through the info on the controller and with my [very] limited electronics knowledge just about understand it. By the time that this unusually seasonal weather fades away I should have got everything ready to start producing my boat from the current collection of various materials and bits and pieces. The bags will come in useful as I plan on installing more than one diving system in this boat,
Trevor

A nice morning down the pond at Barrow. Bright and chilly.

Trying 2 of my subs (Resurgam and Charlie 2) both now with piston tanks fitted.

Both working well - working up for the season!

David