Electronics whizz needed, Oxfordshire area

Need technical help on some problem? Let us know and we will see what we can do
Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » February 6th, 2019, 11:10 pm

I'm looking for assistance with the wiring for my two FN5 turrets, which will involve making a wiring loom for each with fine-wires, and some form of multipin connectors and external switches to connect the loom to the rest of the airframe. Each turret has 6 lamps, typically "grain of rice" bulbs, and an electrically-driven motor and reduction gearbox for the gun elevation. The traversing arrangement is not yet designed.

It'd be useful if a volunteer to come and see the work, advise and specify suitable miniature connectors, returning at a later date to help with wiring it all up once I've made the looms to suit.

(edited) I should have added that I'm happy to defray transport costs, and that the circuit-planning side is also a weak area for me.

Regards

Tim Huff

Steve Perry
Posts: 227
Joined: July 12th, 2015, 7:47 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Steve Perry » February 7th, 2019, 1:09 am

For mulipin connectors I suggest the white JST ones of the type used on balance leads, ebay item 232383796538.

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » February 7th, 2019, 4:09 pm

Thankyou SO much, that's incredibly useful. Not knowing what these were called exactly I'd spent hours and hours trying to figure out what connectors were the right size.

Nigel Cox
Posts: 67
Joined: July 21st, 2014, 9:20 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Nigel Cox » February 8th, 2019, 11:18 pm

Have a look at this https://cpc.farnell.com/c/cable-leads-c ... -terminals you will see the JST connectors come in many different styles and contact numbers

Steve Perry
Posts: 227
Joined: July 12th, 2015, 7:47 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Steve Perry » February 10th, 2019, 12:38 am

If you need something to mount the solder pin sockets on then try Verostrip, this is srbp board drilled with holes to suit with strips of copper on for soldering to.

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » February 20th, 2019, 7:29 am

Thanks, I'll look into that. At the moment I'm just looking to make the wiring-loom for the two turrets so I can tidy away the rats-nest of wires.

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » May 30th, 2019, 7:16 pm

Hi all,

I now need to collaborate with someone in the North Oxfordshire area to help design and build a suitable servo-driven mechanism to raise and depress the gun-cradle on my model FN5 turrets, and to traverse the turrets. The previous "home-made" elevation servo, completely concealed within the shroud around the ram did work, but, was too anaemic to drive the mechanism reliably. Another issue was that only one of the two rams was motorised, and the asymmetric movement added to the power required to move the cradle.

I'm now looking to have a rotating bar, driven by a servo, to in turn drive both "rams", but need help.

Space is very tight, and I have little or no knowledge as to what types of servos are available/suitable, but I need to finalise the design of this so I can move forward with the cupola builds. If there's anyone in my area who'd like to help with this, I'd be most interested in working with them on this.

Steve Mansell
Posts: 222
Joined: March 1st, 2012, 11:59 pm
Location: Farnborough, Kent
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Steve Mansell » May 31st, 2019, 6:04 pm

Tim, I'm not sure how much room you have, but it may be an idea to look at linear servos operating as the rams.
I'm sure you'll get it sorted somehow, can't wait to see the finished article!
Cheers
Steve

Steve Perry
Posts: 227
Joined: July 12th, 2015, 7:47 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Steve Perry » May 31st, 2019, 10:03 pm

Are you using the rotating shaft as a screw or to operate cams ?

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » June 4th, 2019, 5:24 pm

Probably cams, I would think. I really need to talk this over with someone, prefereably in the workshop where the problem can be viewed in the flesh so to speak.

I now know that both rams need to be driven with identical force applied to each. If this isn't done, the asymmetric effect greatly adds to the friction resistance to movement. So Ideally, there'd be one servo rotating shaft, shorter arms of which drive the moving part of the ram through slots in the forward face of the ram. There are, however, two major problems with this method, one is that it'll be hard to fit in the cosmetic "hydraulic" pipes; and secondly that the bottom parts of the ram pivots about the lower trunnion, which complicates the drive mechanism from a common shaft to drive both rams equally.

Barrie King
Posts: 157
Joined: December 4th, 2008, 9:35 pm
Location: Retford, Notts
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Barrie King » June 4th, 2019, 8:10 pm

Have you looked at the mini hydraulics as used by the mini excavator builders?

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » June 5th, 2019, 8:16 am

Barrie King wrote:Have you looked at the mini hydraulics as used by the mini excavator builders?


That's an interesting idea. Are they pneumatic?

Barrie King
Posts: 157
Joined: December 4th, 2008, 9:35 pm
Location: Retford, Notts
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Barrie King » June 5th, 2019, 8:52 pm

No the are hydraulic.

Timothy Huff
Posts: 170
Joined: January 23rd, 2018, 4:12 pm
Contact:

Re: Electronics whizz needed, Oxfordshire area

Postby Timothy Huff » August 28th, 2019, 7:49 pm

Hi all,

This is by way of an "AAR" to the posed questions. I eventually went with two SMC pneumatic double-acting pneumatic rams, with flow control valves (needle-valve restrictors) to slow the extension and retraction rates which would otherwise be more on/off than analogue. I intend to try and design and build a valve to give fine-tracking control for small movements of the servo, with a linear increase in movement of the rams as the servo moves from the neutral point. Such valves do exist commercially, however, they're all electrically controlled, large, heavy and 24 v! And it's an interesting problem.


The pneumatic rams are a little longer and thinner than they should be, so I've made some 3d-printed cladding pieces to make them more closely resemble the original rams. This has had the side-benefit of also making it impossible to mount the two rams at different positions.


On the subject of wiring, I was provided with a large number of different JST/XA connectors and pins, and after a false start, procured the correct crimping tool. I then spent an entire day practising crimping these on scraps of the same gauge of wire as the turret services, before attempting the wiring work. I would heartily recommend such practice as it is something of a "skill" I found.

All the JST connectors were trimmed of excrescent plastic, and were airbrushed black to make those that couldn't be concealed resemble the profusion of cosmetic transformers etc around the turrets.


Black heat-shrink tube was used to cover "modern" pvc insulated wiring, again to make it less visually striking, relative to the cosmetic wiring made from silk-covered wire hand-dyed to resemble wartime wiring.

So, thanks all of you who helped with suggestions, all were most valuable!


Regards,


Return to “Technical Help required”

Who is online

Users browsing this forum: No registered users and 3 guests