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Author Topic: Information on this circuit  (Read 2740 times)

Seaspray

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Information on this circuit
« on: August 29, 2019, 08:09:25 PM »

I've inherited this home made circuit and need to know more about it before connecting it up to the system. Two MFA Torpedo 500 motors @ 4.5 v - 15 v D.C (twin props ) Two Hitec SP 6/10 amps / 6 v-8.4 v ESAs . I believe everything is circa 1999 ish. Each ESC has its own battery pack Tamiya connector with in line fuses. Could do with help on what circuit it is for sure, how to connect the T and R Futaba  connectors to on the receiver.  See pictures
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coch y bonddu

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Re: Information on this circuit
« Reply #1 on: August 29, 2019, 08:13:49 PM »

Those were sold on ebay a few years ago darned good mixers they are.....R is connected to the esc as it is RUDDER...T is Throttle.


Can you post a picture of the circuit board outside the plastic bag as I can not remember properly where the esc connectors plug into and the rudder




Dave
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Netleyned

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Re: Information on this circuit
« Reply #2 on: August 29, 2019, 08:19:12 PM »


R & T to RX rudder and throttle channs
Outputs to port and Starboard esc's possibly.

Ned
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RST

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Re: Information on this circuit
« Reply #3 on: August 29, 2019, 08:49:08 PM »

I remember those on eBay -still selling them not that long ago but not seen them for a few years now. I'd agree r is rudder, t is throttle. The 6 pins those leads are connected to on left look like "pass through" so you can still connect a centre esc and rudder to, then the pins on right look like the two sets of 3 ESC pins.  Not 100% sure, just my take but seems to concur,  and similar set-up for other mixers I have. Just make sure usual bla blah bla only one bec allowed per esc if they're both bec enabled etc.
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Seaspray

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Re: Information on this circuit
« Reply #4 on: August 30, 2019, 07:42:55 AM »

Thanks Gents
Sorry but I don't want to take the plastic off the circuit because it is very tight and wrapped around some components which may cause damage I left out two other pieces of info The connector up on the left hand side is correct but there is a R on the  board top of it and a T below it just above the word mixer. I think the port  esa goes into the top right connection marked port and stbd esa goes into the stbd marked connection below it but which way round does the connector pins go. I've also got a servo for the rudders would this just go into the Rx or somewhere on the mixer. This setup is new to me and I don't see much info on the net. Will have to put a battery in for the Rx as its not BEC
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DaveM

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Re: Information on this circuit
« Reply #5 on: August 30, 2019, 08:15:08 AM »

If you have a multimeter or a continuity tester then you can trace from one of the black wires on the Rx connections to the equivalent pins on the headers for the ESCs. The usual convention for PCB design is to run the negative land all the way around the edge of the board, so I would guess that the ESCs are connected with their black wires on the RHS when you view the board as pictured.
DaveM
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Seaspray

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Re: Information on this circuit
« Reply #6 on: August 30, 2019, 10:26:01 AM »

DaveM
Cheers have never worked with mixers before and thanks for a good bit knowledge. I am hoping to keep everything vintage on the model.


Martin
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malcolmfrary

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Re: Information on this circuit
« Reply #7 on: August 30, 2019, 12:12:15 PM »

Thanks Gents
Sorry but I don't want to take the plastic off the circuit because it is very tight and wrapped around some components which may cause damage I left out two other pieces of info The connector up on the left hand side is correct but there is a R on the  board top of it and a T below it just above the word mixer. I think the port  esa goes into the top right connection marked port and stbd esa goes into the stbd marked connection below it but which way round does the connector pins go. I've also got a servo for the rudders would this just go into the Rx or somewhere on the mixer. This setup is new to me and I don't see much info on the net. Will have to put a battery in for the Rx as its not BEC
As RST said in reply#3, the left hand sets of pins are through connectors to allow easy connection of a rudder (R) servo and, if required, an ESC for the (T)hrottle of the center motor if fitted.
As Dave said, normal practice when deigning boards is to try to have the ground rail around the edge of the board, so when plugging in, it is usually a safe bet to have the black wire of the plug (brown for some) toward the outside edge of the board.
The -ve (ground) connection of the radio battery will need to be connected to the -ve of the main battery, since the ground line connections between unit and radio have been missed, probably to avoid ground loop problems.
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Seaspray

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Re: Information on this circuit
« Reply #8 on: August 30, 2019, 12:27:37 PM »

Malcolmfrary
Thanks for the information might get to the model later to night and have a good look




Martin
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Seaspray

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Re: Information on this circuit
« Reply #9 on: August 30, 2019, 07:37:47 PM »

Manged to get the rudders working through the mixer by plugging into R socket. Took a while as I could not get my 2.4 radio to bond a bad Futaba switch. Tackle it tmo.
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Seaspray

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Re: Information on this circuit
« Reply #10 on: August 31, 2019, 07:59:53 PM »

Everything working now. Rudders activate the motors on turning them Both motors run smoothly now forward and reverse. However I have changed the radio gear to my Hitec Ranger because both sticks have a spring loading centering. So when I take my hands of the sticks everything stops Batteries are a little too big for the battery bays there 8.4 volt might get 7.4 volt one. Believe there shorter.


I may consider putting the rest of this build on Mayhem as well as the scratch build of the Canadian Icebreaker I am just starting build.
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RST

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Re: Information on this circuit
« Reply #11 on: August 31, 2019, 08:36:27 PM »

It looks an interesting model. Particularly the stern which looks could be quite wet with the opening there?  Did I see the old gold 10A "brick" esc's before. Loved them. For what they were they opened up a cheap enough alternative to resistive speed control.  I've no idea where mine went over the years. Always wanted them back. They used to take allot of abuse from me rather than just fail. Trick with modern radios I find is to choose one offering the spring conversion kit, I personally wouldn't do without.
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Seaspray

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Re: Information on this circuit
« Reply #12 on: September 01, 2019, 07:31:07 AM »

RST I did notice the stern would be an issue and a further look into it to decide if I can get to the rudders from inside the motor / battery area. if so I'll seal as a hatch. If not  its a removable one. The old  brick" there still up  for sale on the net here and there, unfortunately their not BEC. I've got an old battery holder I use and can charge the 4 AA rechargeable batteries in the holder to power the Rx. Just takes up a little more room but there is plenty in this model. I haven't looked yet to see If the Planet 5 has a conversion kit. If so I will fit one. Mind you I prefer the older type radios with that function .
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malcolmfrary

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Re: Information on this circuit
« Reply #13 on: September 01, 2019, 09:39:07 AM »

In their day, the gold bricks were things of wonder, but had to be used within their limitations.  When they were designed, they were stuck with using possibly the most horrible power transistors ever, only having a current gain of about 20.  To get 10A out of them, they needed a LOT of current to drive them, which meant that the resistors driving the output transistors got very hot.  8.4 volts really was the limit if the heat off that resistor (a bit over 4 watts in a confined space) was not going to cook both the resistor itself but also the board near to it.  6 volts was the minimum if the resisor was going to pass enough current to properly switch the output transistors on.
Really liked the screwdriver adjustments, though.  Apart from internal cooking, what killed a lot of them was users not realising that the adjustment was a small screwdriver held in finger and thumb to be gently twiddled, not a target for a bayonnet charge.  That, as some thinking that they could be wired up like Bobs Boards.
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Seaspray

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Re: Information on this circuit
« Reply #14 on: September 01, 2019, 10:48:43 AM »

malcolmfrary I haven't yet done a read up on these ESAs but I did notice bottom left hand corner an image of a screw head. I did take it was a screw and thought it was for adjustment like some of the Electronize ESAs. If everything is running o.k. would it best left alone ?. Two Hitec bricks are in the model on this tread they have two covers where the screw image are not torn open,  ie never been adjusted.
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malcolmfrary

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Re: Information on this circuit
« Reply #15 on: September 02, 2019, 09:26:46 AM »

Just the one adjustment on a Hitec ESC.  Used to set the center to match the transmitter. 
Electronise ESCs had two adjustments, one for center and another that tweaked the deadband, and, coincidentally, the end points and the rate of speed change. 
Same problems on both, users more used to hammers and chisels and muscles rather than small screwdrivers and finger and thumb adjustments and an iability to read the labels saying which wires were for power supply, and which were for connection to the motor.
Hitec designed theirs around the idea of a Hitec based system, Electronise's Electonic Speed Control had to work with anybodys transmitter.
I have no doubt that, having survived this long in good condition, they should continue giving good service. 
The old ESCs, because of the way they worked, gave a low, rumbling growl from the motor.  Modern ESCs tend to cause the motor to whine, one of the prices of progress.
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Seaspray

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Re: Information on this circuit
« Reply #16 on: September 03, 2019, 07:59:54 AM »

malcolmfrary Thanks for the information on these ESCs ( hey I got it right not ESAs ) I believe they have never been used and working fine at the moment. All the running gear including the ESCs ( l,o,l ) are fitted in place and the deck put in place. Moving on to build the cabin. Its when the model is in the water I will be listening to the sound of the motors / running gear as they'll  have a load on them. I think for what it is, the mixer Its so simple. Had I been able to make the PCB I would make a few for myself and others.
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malcolmfrary

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Re: Information on this circuit
« Reply #17 on: September 03, 2019, 09:06:33 AM »

It might be interesting to know what is underneath the 8069 label.  According to the data sheet, an 8069 is a 1.2 volt reference with only pins 4 and 8 connected.  Taking the average of two inputs and creating an equal and opposite pair of difference outpts needs something more complex, probably with some serious internal programming.
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Seaspray

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Re: Information on this circuit
« Reply #18 on: September 03, 2019, 05:07:18 PM »

malcolmfrary


I looked into the 8069 chip to me it was just a shunter / voltage regulator old style through the hole. I see some later ones are smt. Only way I know of seeing whats inside it, is to do a sum check and reference that to a data sheet.
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malcolmfrary

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Re: Information on this circuit
« Reply #19 on: September 04, 2019, 08:57:52 AM »

I have a sneaking feeling that the 8069 is a label applied by the mixer maker, not the chip manufacturer.  "Proper" chip numbers are generally quite difficult to read, usually being quite small and printed in mid grey on a black background, and carry much more than just a number.  It is probably a PIC (or similar) carrying a custom program, probably not at all easy to back engineer.  The presence of a clock crystal is a good clue.
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Seaspray

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Re: Information on this circuit
« Reply #20 on: September 04, 2019, 10:29:48 AM »

Hopefully I have read you right. After programming a chip it is labelled by the prom programmer as a means of  I.D. for further reference down the production line. The manufacture doesn't programme the chip as in my case it was M.O.D  employment. Some may do for simply day to day simple ( burns ) programming like toys, mixers.and alarms. Once a chip is burnt PROM type thats it it can't be ( wiped ) erased. Unless your  working with EPROM it can be. Then there is the gran daddy the EEPROM. All this info is on the net


Onward  with the building of the model had a gut full of electronics and gyros
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DaveM

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Re: Information on this circuit
« Reply #21 on: September 04, 2019, 11:03:18 AM »

That's about the size of it. All of the 8-pin microprocessors I've used are PROM types - only the 14 pin+ types have been reprogrammable. It is usual for a chip to be code-protected during the burning process so that reading the code later by anyone not already in posession of it will not be possible. I imagine the label is a subterfuge to disguise the thing even further - no circuit would work in that way with a 'proper' 8069. Where necessary I used to sand off the legend with emery cloth!
DaveM
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Seaspray

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Re: Information on this circuit
« Reply #22 on: September 04, 2019, 11:32:38 AM »

DaveM
Emery cloth, nice one. The eeproms I burnt were  32 pins and were erased using some kind of infra red. Well so we were told.
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C-3PO

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Re: Information on this circuit
« Reply #23 on: September 04, 2019, 12:31:47 PM »

The mixer unit I have that was labelled with an "8069B" sticker has an 8 pin EEPROM Microchip PIC 12F629 chip under the hood...

https://www.microchip.com/wwwproducts/en/PIC12F629





C-3PO
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C-3PO

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Re: Information on this circuit
« Reply #24 on: September 04, 2019, 12:38:31 PM »

oops
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