Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: essex2visuvesi on August 30, 2010, 02:25:20 PM

Title: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on August 30, 2010, 02:25:20 PM
Im in the planning feasability stage of building a Deans DKUW and I would like to make it work on both land and water.

The TX im using is a 6 Channel with a landing gear switch on ch 5

what I would like to do is make the vehicle run in land mode (steering servo, Gear shift (3 speed transmission from a tamiya tractor truck), and drive motorESC) when the gear swich is in position 1 and water mode (Rudder servo and separate prop ESC) when its switched to Position 2

Each speed controller would would have its own drive battery

I understand it could be done with relays and microswitches but I was curious if there is there a device on the market that will allow for switching between servos in this way

Links to DIY builds would also be appreciated
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: Ghost in the shell on August 30, 2010, 02:30:48 PM
Here's how i'd do it

I would be tempted to 3 receivers and 3 radio switches from action or robbe, operating on a BEC, say from mtroniks viper esc's with a radio microswitch from the master esc on-off switchon the battery side of each one.  so when in up, the the master RX would be told to power up the land drive, when you hit the water flick the switch down to turn off the road drive and break the electrical connection between the esc and wheels, this is to prevent a dynamo action potentially damaging the esc.  it would also through the other switch power up the wet drive

another (much cheaper) option would be to have two esc's and a switch, the two esc's would share a common negative, and the radio switch would divert power to either the road transmission esc or the maritime drive esc.  the switches have a 3 pin block and the metal reed flicks betweem 1+2 and 2+3, so...
in pin 2 you have you red wire from the battery,
in pin 1 is the wire to the road esc,
in pin 3 is the wire to the maritime drive esc

in the down position, the switch would be joining 1+2, so 3 would be dead
in the up position shw switch would be joining 2+3, so 1 would be dead.  


for unsurance you could put a second relay between the esc for the wheels motor, and the wheels motor, this is to prevent any possible damage from a dynamo action frying your esc, and esc's dont take kindly to power coming in from the motor end.  
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: FullLeatherJacket on August 30, 2010, 03:53:36 PM
If all you really need to do is use the Gear switch to transfer the control of the "throttle" stick from one ESC to another then our resident forum techno-dude PMK has a little gizmo called a Channel Hopper which will do just that. In fact he has one which will switch over two separate channels i.e. you could switch the steering over, too. No need for three of anything or the attendant spaghetti wiring loom.
FLJ
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: Peterm on August 30, 2010, 04:54:17 PM
PMK,  tell us more, please.   Pete M
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on August 30, 2010, 05:25:33 PM
If all you really need to do is use the Gear switch to transfer the control of the "throttle" stick from one ESC to another then our resident forum techno-dude PMK has a little gizmo called a Channel Hopper which will do just that. In fact he has one which will switch over two separate channels i.e. you could switch the steering over, too. No need for three of anything or the attendant spaghetti wiring loom.
FLJ

Thats exactly what I need :)

PMK more infor please!
:D:D:D:D
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: barriew on August 30, 2010, 06:07:42 PM
I think that this is what FLJ is referring to - unless PMK has got something else up his sleeve ;)

Barrie

http://www.pm.keirle.com/1_gadgets/channel_extender/channel_extender.htm
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: 787Eng on August 30, 2010, 06:11:39 PM
Is you radio programable and have programable mix's?
if it has, it's very easy to do with your radio TX....

Mark
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: Peterm on August 30, 2010, 06:22:38 PM
PMK,  an excellent well-written and easily understood article.   Have already got my soldering iron warming up.  Many thanks,  Pete M
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: FullLeatherJacket on August 30, 2010, 06:25:17 PM
I think that this is what FLJ is referring to - unless PMK has got something else up his sleeve ;)
This is very much Pete's MK1. The more recent one uses a single PIC16F628 microprocessor and fits neatly inside the same case as our P43 switcher. When he feels a bit more in touch with the world after his medical 'malarkey' then we might progress this into a new ACTion unit. Meanwhile you'll have to implore him via PMs!
FLJ
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on August 30, 2010, 06:50:42 PM
So I could in theory build two of these and the non proportional inputs for each unit could both be connected to the same port (the laning gear switch in my case) on the RX using a Servo Y lead

If thats the case then my problem is solved.

Looks like im shopping at maplins lol.
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on August 30, 2010, 07:28:13 PM
Pete M: Has anyone ever told you that you're a real smoothie? Top thanks for the neat comments. Flattery will get you everywhere.

So I could in theory build two of these and the non proportional inputs for each unit could both be connected to the same port (the landing gear switch in my case) on the RX using a Servo Y lead.

As Dave has already stated, the Mk2 PIC-based version will control up to two separate channels via your landing gear switch - which in theory would save you the trouble of building 2x Mk1 versions... if that makes sense. I can post the full build-it-yourself details but you will need the means of stuffing the PIC microcontroller with the relevant HEX code... or just ask and I'll supply the pre-programmed chip.
Although, what with one thing and another and everything going belly-up recently, I would ask that you give me a bit of time until I'm more in touch with the real world again.
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on August 30, 2010, 08:34:33 PM
Absolutely perfect!

If you could post or PM the stripboard plans that would be great

Theres no rush.... its still in the planning stage so get yourself better first

And thanks for all the help guys!
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: Peterm on August 31, 2010, 08:41:36 AM
PMK,  That`s 80 years of experience.   Not into PIC`s but it looks good.   Pete M
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on September 18, 2010, 10:37:20 AM
As Mr 787Eng has already said, you can pretty much do all that you want to do if your radio has programmable mixes.
Else, here's the words & music for the Mk2 homebrew version:

http://www.pm.keirle.com/1_gadgets/channel_hopper/channel_hopper.htm
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on September 18, 2010, 01:31:59 PM
Thats brilliant thanks

I dont have the facilities to Program the PIC tho :(
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on September 21, 2010, 05:46:32 PM
The blank PICs themselves cost somewhere around a tad over 2.00 each. The code is free.
Your call?
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: John W E on September 21, 2010, 06:16:35 PM
hello there PMK  :-)) how ya doing me owld marra, hope all is well.

Hows about giving me a price for you to put a kit together of the components and a pre-programmed PIC chip; okay; and then we will discuss some business here eh...I wouldnt mind having a bit play around with one of these gadgets.   I have another idea which ----- combination of a couple of these linked together with another module --- could make some interesting stuff.

aye
john
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on September 21, 2010, 06:43:31 PM
hello there PMK  :-)) how ya doing me owld marra, hope all is well.

Hows about giving me a price for you to put a kit together of the components and a pre-programmed PIC chip; okay; and then we will discuss some business here eh...I wouldnt mind having a bit play around with one of these gadgets.   I have another idea which ----- combination of a couple of these linked together with another module --- could make some interesting stuff.

aye
john

If you put a kit together Ill take one too :)
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: colin-d on September 21, 2010, 07:04:24 PM
count me in on that one as well... kit .. kit... yes please
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: roycv on September 21, 2010, 08:05:42 PM
Hi PMK, great to see some electronics.
Do you do a servo stretcher circuit? i.e to increase the servo to travel?

I know I would have to cut some tags in the servo if necessary but for small yachts a servo can make a good arm winch.

I already use one of the Action servo slowers and that does a good job of slowing an arm winch that would otherwise whip round too fast.
I have done very little electronics since working with a friend to make the water level control circuits for a boiler, back 20 years ago now.
Very much enjoy new ideas and I had never heard of a channel hopper before.
regards to all, Roy
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: John W E on September 21, 2010, 08:14:32 PM
hii there roycv

if you recheck ACTion's website I am sure they do a servo morpher or something like that  %%  cant tell you what the P number is but that increases the throw of a standard servo when wired in with it.

it also can be used to slow the servo down;  if you want to start and modify a standard servo, to increase the throw, you must hack into the variable resistance which is linked into the gearing and you insert two resistors to increase the resistance of the pot..   If you do a Google search on this subject, you will find there is lots of information on how to modify servos.   I think if you just type in Modifying Servo it comesup - food for thought my mate.
this may help http://www.youtube.com/watch?v=bpO7XMXGzfw&feature=related
aye
john
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: Prophet on September 21, 2010, 08:17:43 PM
P96 SERVOMORPH  that's the one your on about Bluebird  :-))
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on September 21, 2010, 08:22:00 PM
When you say kit, do you mean it should include everything from the Veroboard to the ABS box also?
The reason for asking is because it takes a surprising amount of time to file/trim the Vero in order for it to fit inside the box. It's dead easy to do but you'd be surprised how long it takes to file a bit of Vero. Would a kit of parts mean that the Vero has to come pre-trimmed, or are you okay with trimming it to size yourselves? If it has to come pre-trimmed, then that means that I'd probably have to charge a bit extra for the labour, blah And I'm useless with that side of things - I wouldn't have a clue of how much to ask.
Any ideas?
The rest of the components are just easily-available plain-jane stuff. For instance, you'd need at least three servo extension leads, or maybe even separate male/female servo plugs/sockets. Then another few shillings for the crystal. Then there's the ABS box itself (I get mine from Dave at ACTion). Basically, if you were to purchase all the needful yourself, the whole caboodle should cost no more than a couple of pints plus the cost of postage for the pre-programmed chip.
As you may have sussed already, I don't possess the necessary brains to be a successful business contender to Alan Sugar, so I don't have a clue of how much to charge for a kit of parts. I leave all the clever stuff like that to folk like FLJ.

To answer Roycv's question: No, I don't - sorry.
Take a look here: http://www.action-electronics.co.uk/mixers.php , then scroll down to "P96"     
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on September 22, 2010, 06:07:05 AM
Untrimmed veroboard is fine for me also the box is optional as sods law says the box will be the wrong size to fit where I want to use it lol
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: colin-d on September 22, 2010, 09:14:46 AM
i don't need the box either... the board i can do my self, so long as there is instruction, like on the website mentioned..

The Kit just to include all the parts (electronic) and a piece of board large enough to place the parts, plus a print out of the website, and probably the servo cables, but the cables are not a must...

the price you say the chip is about 2 pounds the rest of the components are really pennies, so i think a tenner would be reasonable..!!  :kiss:

what do you say  :-))
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: essex2visuvesi on September 22, 2010, 12:01:54 PM
10 quid or there abouts and I think you would sell quite a few
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on September 22, 2010, 01:30:18 PM
Oops!... crossed wires. It's not about money. It's only because y'all asked for a kit of parts.
I've taken the liberty of trimming the stripboard to size but since you don't need the ABS boxes I've left the four corners intact.
I'm waiting on an order for the servo leads, will then pop it in the post. How about PM'ing your home addresses this way?

Colin-d, my printer has recently died. I shan't be able to send the relevent printouts so you might want to keep this post for reference.

(http://s1.postimage.org/KNTk0.jpg) (http://postimage.org/image/2n0fjyex0/)

Although not shown in the photo, the pre-programmed PIC *is* there. And the heatshrink is only included for in case you want to sleeve the servo leads as per the website sketch.
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: colin-d on September 22, 2010, 01:56:00 PM
PM on its way, no Probs about your printer..
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: PMK on September 26, 2010, 04:55:16 PM
It's your lucky day. I've just taken delivery of a swanky new printer - means you will now receive all the relevant bumph, total of four sheets.
Again, I've taken the liberty of also printing/pasting a component overlay to the component side of the stripboard. In essence, much like a dedicated printed circuit board, means that all you have to do is stuff the components in the appropriate locations, thereby reducing the chance of soldering any wire link or component in a wrong location on bare stripboard. You'll see what I mean when the pkg arrives.
Will post it to y'all on the morrow.

(http://s1.postimage.org/aZvq9.jpg) (http://postimage.org/image/macj3fb8/)

(http://s1.postimage.org/aZCUA.jpg) (http://postimage.org/image/mahhpgsk/)
Title: Re: Swiching between 2 servos using a spare TX channel
Post by: roycv on September 27, 2010, 01:18:01 PM
Hi Bluebird, thanks for your response.  Yes I have doctored a few servos in the way you mention, find they can be a bit twitchy but I was doing this before we had such an incredible range of servos available.
kind regards Roy