Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[DocMartin]

During a recent acquisition of vintage RC gear (from a submarine enthusiast), a two channel device (pictured) was included without any related "manual or instruction sheet".


It appears to be some kind of mixing board, but its function is not overly clear to me.  I am reaching out to all the experts to see if the board can be identified/described.The board has two Futaba type male connectors that I attached to channels 3 and 4 of my RX.  The outputs #1 and #2 (shown) have a singular mini potentiometer-like adjustment, respectively.  To these, standard servos were attached.  When tested, the following movements were observed:
Upward and Downward movement (CH3) results in simultaneous clockwise and counterclockwise motion of the servos (identical paired movement).
Left and Right movement (CH4) results in the two servos moving opposite of each other (i.e. one servo turns counterclockwise as the opposite turns clockwise) with Left full stick followed by the mirrored servo movements (clockwise + counterclockwise, respectively) with Right full stick.


The singular mini-pot seems to reduce/increase the servos angle of rotation equally (for the channel movement (CH3 or CH4) selected.

Inspection of the circuit board shows a Microchip PIC 16C71X micro-controller and 4.000 MHz crystal along with many SMD caps, resistors, etc on the opposite side.  No discernible manufacturer markings are seen.

Does anyone have a clue as to the designed function/purpose of this device?? 

[HMS Invisible]

...
Does anyone have a clue as to the designed function/purpose of this device??

A wild guess is a 1:1 mixer for an X-tail sub.
The pot adjustments could be either gain or end stop.

[JimG]

Another possibility is a rudder / throttle mixer for a twin screw boat. The outputs go to two speed controllers, throttle operates both motors as one while rudder puts one motor forward and the other reverse allowing it to spin on the spot. When in rudder is used in conjunction with the rudder one of the motors will slow down tightening the turn. The adjustment wil be for the amount of mixing between the channels. I used an older version of this to give motor only steering in the small Billings Coast Guard cutter.
Jim

[Bustergrunt]

Looks like a Hoobyking/Turnigy V-tail mixer for model aircraft, minus the normal heatshrink covering

[Circlip]

So why the crystal?


 Regards  Ian.

[Martin (Admin)]

.... Timing clock?

[Mosfets]

.... Timing clock?

I would go along with the crystal being for the timing.
Although these microcontroller have an internal clock the addition of a crystal and two capacitors  increases the accuracy of timing.

[roycv]

Hi all I have something very similar with instructions dated April 2004, so quite old.
The two leads are rudder and single throttle., so a single throttle to run 2 motors.  This splits into 2 o/p's each going to an esc.
My one is labelled throttle and rudder for the leads and port and starboard for the o/p to each esc.
However there is no pot to adjust but the blurb says the rate switch on the Tx can be used to adjust mixing.  It also has a crystal, so can't help with that bit.

Essentially Jim G thread 2 is right.

There is a website mentioned http://www.kleefeld.freeserve.co.uk/model/barry/pic01.htmbut this does not seem to go anywhere.

I bought my one on ebay for a tenner and will be using it soon, the seller said he had no idea how to use it!

I have another similar unit I bought from Aliexpress labelled EDJP1053.  This has a 2 wire connector for battery (like the old Rx type), a single servo lead to throttle in Rx. and a single wire lead which goes into the rudder signal only, no + and -.  This would give tank control but if the wire was connected to a rudder servo in parallel it would give a similar unit as above.

I should have added that this unit includes the esc and connects direct to the drive motors.  It is called a differential esc.

On the egg sucking side can I assume the large capacitor has not been mistaken for a pot?

Hope this confirms what has been said.
Roy

[roycv]

A further check reveals that Freeserve stopped working in 2016.
Roy

[DocMartin]

Roy:
The age of the mixer sounds correct.  I acquired a lot of vintage electronics from the early 2000's.
Would you be able to post a copy of the operating instructions??
Thanks.
DM

[roycv]

Hello here are the instructions.  It suggests a kit but this looks like a ready made item.
Not sure if I know how it all works!  Especially mentioning the 3rd. engine.


Good luckRoy

[roycv]

Hi sorry not sure where they went!  Another go.
Roy

[DocMartin]

Thank you all for your feedback and postings.  Special thanks to Roycv for posting instructions!

Following Roycv's instruction sheet, I tested the outputs using dual ESCs.  The mixing function of this setup followed similarly to the setup testing two standard servos.  Depending upon the channel chosen, the motors rotated in a paired motion or  a counter-rotating manner, respectively.  Adjustment of the individual potentiometers either increased or decreased the maximum speed of BOTH motors TOGETHER.  There was NOT any way to slow the rotation of the motors INDEPENDENTLY. 
Given the lack of differential speed control, this mixer would make steering by motor(s) alone, difficult at best.  Control of rudder function could not be assessed with the setup mentioned.  Rudder function would require control via another channel, independently.

From this series of tests, the purpose of this mixer best matches the post left by HMS Invisible.  I am apt to believe this is an X-tail mixer from the early 2000's.