TinyTwo Speed Controllers

[Rapidrory]

Cheers for the advice Peter

Yeah, I had a look through your thread about selling ESCs, and very quickly decided not to sell them more officially :L

I've checked the specs on the voltage reg i'm planning to use: from the 'Output Short Circuit Current vs. Differential Voltage' graph, It shows that at 12V differential (so 18V input) it's capable of outputting about 1.1A. At a 6V differential voltage (so 12V input) where it would normally run on a 3 cell, it can manage a good 1.6A. It doesn't state for how long, and would heat up pretty quick dissipating 13.2W at 18V, but should would work OK if it was only running the Rx at that point. I'll have to run some more tests! I may have to say 18V as an absolute maximum voltage, with 12V or less being recommended. I'm using LDO regulators, and the drop out is 1.2V differential at 1A, so should be fine on a 2 cell. I tested it today running on 12V whilst driving a servo as well. My present setup has a 5V fixed regulator of the same type, and that barely got warm... although according to the power supply the servo was only drawing about half an amp, so it's not an ideal representation...

Yeah, I have a non-reversible lead on there too; I was more than a little concerned about plugging this thing in backwards after how long it took to make :L

Ah ok then no it wouldn't be compatible with the Corona Rx, as it relies on the pulses being sequential I'm afraid

Haha, well I'm looking into getting a batch of 48 boards professionally printed and set up so I can re-flow solder a load at once; soldering up one by hand is bad enough! :L

[joey_picus]

I kind of figured that might be the case, I'll still happily buy a couple off you though, if you're willing to sell to me I might actually be interested in having them as a bare board with no leads, as that would save you time and effort and I find soldering weirdly relaxing...

[Hogi]

will this model be fitted with a mixing switch? after seeing the effectiveness of epq I may have to think about building a four wheel drive ant at some stage.

[Rapidrory]

I theoretically could make it compatible, but not with out a pretty fundamental change to the firmware... It's taken me a month of coding so far to get this version working so unless i'm feeling particularly bored one day, there probably won't be a compatible version :L
Yeah, I was thinking of having an option with no leads; means you can solder in only what you need and save yourself some space/ me some time.. might even be slightly cheaper :L

Mixing switch? The firmware does the mixing atm, and I may do a non-mixing version if there's a demand for that, but there's no way of switching between the two once it's been programmed if that's what you mean..

I'm gonna try running some more scientific tests on them next week when I have a bit more time in the uni labs; I don't have the kit to run proper tests in my room. If anyone's curious to have a look at them, I should be running the prototypes in my two robots for the AWS. Hopefully will also be able to show that they're reliable if they last the day (..If :L). I

[BeligerAnt]

Nothing like 3 full days at Modelworld for stress-testing robots (and roboteers!)

If you have a spare input pin on the PIC you could add 2 pads to the board, solder a link to short the pin low to disable mixing, leave it open to enable (default?). This does rely on having a spare pin on the PIC with an internal pullup resisitor.

[Rapidrory]

It's only a 8 pin PIC chip with 6 I/O: 2 for servo signal input, and 4 for PWM signals to motor driver chips.. No spare pins there i'm afraid. But if I did a mixed and non mixed version, It's unlikely that you'd need to be able to switch between the two settings as most people have either a transmitter with mixing or without... It's easy enough for me to program them with different versions of the firmware before shipping though.
If someone really wanted to change it they could either get a copy of the firmware off me and reprogram it themselves if they have the right hardware, or ship it back to me and get me to change it. Though that's obviously not something you'd be able to do regularly..

[peterwaller]

Beware the slippery slope.
When I started doing controllers for other people almost 5 years ago I tried to accomodate all the variations requested but now after types
A, B-60, B-61, B-63, C, D, D2, P5, RL2, HK4, Rx31 I now make just one (Lem1) which incorporates the lemon DSM2 receiver.
Out of interest and if it is not a secret which motor drive chip do you use.

[Rapidrory]

It would hardly stay secret very long if i start selling them! They're a nightmare to use; I probably wouldn't have used them if i'd realized how much supporting hardware they needed...

http://docs-europe.electrocomponents.co ... 04e774.pdf

[BeligerAnt]

Those shouldn't be too diffiult to drive, they should only require a transistor/FET buffer between the gates and the PIC I/O pins.

The thing to be aware of with your board layout is that you won't achieve anything near the datasheet figures for current handling/power dissipation.
The figures are based on a 25 x 25mm PCB mostly covered in copper connected to the FET drain pins to act as a heat sink. Most of the figures also apply to only one die being active, even though all practical applications require 2 active die at a time!

[Remote-Controlled Dave]

These look right up my street!