TOPIC:

Those micro esc I had laying around was not that micro it seems..



Just fits inside the sleeper, but sticks out too far at the bottom.
I later forund a solution regarding a suitable item..


 

That SCX24 motor I was gonna use is way too big.
Instead I took the motor and gears from the blue vintage car.
With the wheelaxle from that and the motor and pinion I got the reduction I was looking for.
Motor is 6mm thick.
Some superglue and styrene later.
The wheelaxle is 1.5mm, so the pinion from the slot car slips right on!


First test fitment


1 Norwegian krone as size ref




It does work!


After a lot of chassis trimming the transmission fits as good as it will (not glued yet)
I ended up cutting the motor side fuel tank off the chassis and glue it to the body as the bits that securing the tank to the chassis would not let it sit high enough.
I could have turned the motor so it poked through the sleeper, but then I would have no room for receiver.




The inner wings of the hood was opned up so it will now have space for the servo


Hood more or less secures the body to the chassis. I will add magnets for the body.


The distance from top of hood to bottom of front axle is 16mm, just as the servo I ordered minus splines.
I hope I can trim the bottom of the servo some so it will move up a mm or two.
Will also have to fabricate a new front axle or buy one.


So for the esc...
After rumbling through my stuff I found this old servo board that measures 16x19mm.
I cross my fingers it still work.
Wires for the pot meter will be replaced by two resistors. Takes less space.
I will also replace the normal servo wires as they are too big. (using clear coated brass wire is my plan)


This just fits inside the roof of the sleeper..


Not sure I will glue the rear axle in before I get the servo as that dictates how high the front needs to be.
I don't want Carolina Squat at all!
 

That's awesome Richard.  I'm stupid but how a servo replace an esc? 

stingray-63 wrote:

That's awesome Richard.  I'm stupid but how a servo replace an esc? 

You're not stupid!

A normal servo has a small motor right?
This is normal mod in crawler world to turn a servo into a winch.
To do this you remove the stopper (a pin on the big gear). 
Now the servo won't stop rotating and you can then use it as winch to make the rope/wire go in or out as long as you make a servo input.
Next mod is to replace the potensiometer with two 2200oHm resisistors, basicly fit two legs together to the center leg of the pot meter and the other legs to the other pins, one at each side.

Now that the gears is removed, the gears can no longer tell the circuit board by the potmeter what is the center of stroke of the servo, or better said, the motor no longer can told what is center (idle).
Two resistors of same value is doing the same as center point of the pot meter. You simply trim your transmitter as usual to find the center point.

The servo is basicly a very small esc. If you move the steering or throttle slow, the servo is going slow, if you move it quicly, the servo will go quicly as well.
Servo motor, or in my case, micro motor will now spin as long as there is servo input, in my case throttle.

You can also use the servo circuit board as led switch if you have a spare channel.
Remove motor from wires, fit leds with right value resistor for the voltage output to the motor wires.
And either glue potmeter in center posistion, or fit resistor as described above.
Now just set end points on your extra channel so lights is on or off (2 pos channel)

Those led switches you can buy is basicly a servo board with built in resistor instead of that pot meter.
I built my first led switch from a old servo about 16 years ago.
I think I was the first one to actually do one in 08 at the scale4x4 forum. Long before a channel on-off switch was available on the market.


I can show a how to on a normal servo from the beginning if it's easier to understand.
 

Thanks a lot Richard.

Here I'm going to show how you can use a old servo as an esc for small projects..


Pick any old servo..


With top cover removed you'll find the gears. Which in most cases can be replaced if you get unlucky or the splines is no good for some reasons..


The marked spot is the stopper, which is the hard stop for the servo to left or right. If you are going to use the servo as winch, this needs to be removed.
It's usually a metal pin, or a casted stop on plastic gears.


With the gears removed you will see the end of the pot meter sticking up. This goes into the big gear and gives a ref point to the board where the servo is in the stroke.


With bottom cover removed you will spot the motor and the circuit board.  Potentiometer or potmeter for short lives above the board.


Here is the guts pulled from the servo. Potmeter, circuit board and motor. There is really not much inside a servo..


There is 3 wires going to the potmeter. Sometimes it has legs and soldered directly to the board..


You can either glue the potmeter after powering it up and find center. Or...
Take two 2200ohm resistors and do like this. The center leg goes to the center leg where the potmeter was fitted and the others does not matter which wire you connect it to.
This hinders the servo to wander, or in my case use it as esc for a small motor..


And here I show how it works as an esc...


 

The battery for the micro rc conversion came today.
Word tiny is really fitting for this!


And after some Dremel work it now fits between the cab and sleeper


Interior still fits


I bought a Power HD 1440A micro servo yesterday and the 10x7mm circuit board is the perfect size as micro esc! Hope it has enough omph to drive the motor.
The circuit board I found last time did not work so that was no go.


Nearly looks lost in there lol


Also bought the little brother of 1440, the 1370A.


As you can see, even at 3.7g, it's way too big for this build. So still need to wait for the one I ordered.



One step closer with this micro rc conversion 

 

My Radiolink receiver that I ordered from Banggood 10 days ago arrived today.
That's fast compared to from other places to my doorstep in Norway 


I also ordered a Radiolink RC4GS radioset today.
Should be here a week from now..

On paper the receiver should fit the sleeper sideways, but the antenna was too rigd and the board was just the right length.
Instead I opted for fit it longtiual with the pins bakwards due the hight. The pins will be cut down and wires soldered directly to it. Servo plugs is just too high to fit under the roof.
The micro servo board (now esc), just fits beside it.


Now that the receiver is taking up space where the battery should go (between cab and sleeper), The battery needs to be relocated.
Luckily it fits on the short wall of the sleeper.


Then it was just the matter of making a wall for the floor so the battery can be secured to it.




This solution actually worked better as all electronics can be fitted to the floor and the body can be easily removed for service.
Speaking of the body. Since one of the tanks now is glued to the body, it now acts as a hinge. Body fit tight down and the hood secure it even more..

Now I only need the servo and I have everything I need to turn this to a rc car.
When the servo arrives, I will find where it needs to be located and then make a front axle that will fit and turn.
After front is done I can then glue in the rear axles.

That's crazy Richard.  You are crazy 🤗🤣🤣🤣👏👏👏👏

Next was to dremel off the transmission part under the steps to create room for the on/off switch


Just enough room to fit transmission.. Had to cut off part of the exhaust.


I needed a small plug for the charging. 2mm bullets is really too long and seems risky.
My LHS has Mini Deans, but I wanted to see if I had something that could work.
Found some spare male sockets from leds to fit a lightkit.
That seemed to be PH 2.0 socket and I hoped I had something in my parts bin to match.
And I did! A old sircuit board from a transmitter had the right female end. Sometimes I'm happy I don't throw away bits and bobs!


That will go here


Some dremel work later, we got a hole in the tank..


I need to shorten the pins for the wires so it will sit further into the tank. I hope to have it flush when finished.
Before I can glue it in place I need to solder on wires and drill holes for them through the floor.



In my electric spare parts bin I also found a XH balance cable so I can make a charge lead for my 1s battery.
My charge can also charge 1s down to 0.1A, my battery is 60mAh so that should work (charge rate 1.4C)


The place I ordered my Radiolink RC4GS transmitter from phoned me today to say it was out of stock, strange as it was in stock at the time I ordered.
For a bit more I then decided to go for the RC6GS transmitter, which has 6 channels. 

The servos is nott far away on the tracking, so I should start on the steering very soon