mosfet mod for piccoz

ph2t · Post by **ph2t** » Wed May 16, 2007 5:18 pm

I was having a look at the PCB last night on the doner heli that talldude gave me and I took some measurements. It looks like it will be possible to replace the stock BJT transistors (there's 2) with the popular IRLML2502 MOSFET we use in the bit mosfet mod.

There are two MOSFETS on the piccoz PCB. One controls the main rotor motor, the other controls the rear prop motor. These two are mixed signal controlled so an increase in acceleration in one results in an increase in accel in the other. (ie: to keep the bugger stable).

Turning left or right is just an adjustment to the speed of the rear prop. I tested this and look some measurements and everything seems to hold true.

I haven't done this mod yet, i'm keen to try though. If anything is to show from how our Bit's ran after the mosfet mod, I reakon we should see similar things here. ie: increased runtime as a start.

The only issue I see at the moment is getting to the bloody PCB. Has anyone got any guides or ideas on removing the body in such a way that you can put it back on later. I take it you just need common sense, patience and a sharp arse hobby knife...

We'll see how we go. Hope to do this mod soon. gotta look for some of those 2502 MOSFETS now, if i've got any, lol...............

SHAUN · Post by **SHAUN** » Wed May 16, 2007 5:22 pm

Carefully run a exacto down the middle.

evoraptor · Post by **evoraptor** » Wed May 16, 2007 7:09 pm

SHAUN wrote:Carefully run a exacto down the middle.

Yea, basically. Carefully, as in REALLY carefully. Theres only so much foam blocking the lipo, so uh, yea.

ph2t · Post by **ph2t** » Thu May 17, 2007 10:24 am

Success!!!!

Here's the stock setup:

Here's the mod setup, with two new IRLML2502 MOSFETS soldered in place of the stock transistors.

It wasn't too hard. The tricky bit was splitting the foam body, but I got there in the end. Justmake sure you use a SHARP hobby knife, this helps bigtime!

Once the PCB, lipo and frame are out of the body it's quite easy to get to. You will need to unwind the little loom of wire that sits in front of the PCB (where you want to operate) to get to the transistors.

I just cut the stock transistors off and put on the MOSFETS.

It's 1:20am here so I can't fly it around the house, Iwill test it tomorrow but already it looks promising. There is definately more power. ie: a lower throttle setting now results in the same hover as a higher setting previously.

Climbing is a lot quicker as well!

Just like the MOSFET mod for bits, this MOSFET mod really does have an impact on performance, quite a bit actually.

Will spill more once I get a chance to fly it around. I'm also hoping for increased runtime, but we'll see, we'll see.....

Very happy.......very happy.......

Clint · Post by **Clint** » Thu May 17, 2007 12:03 pm

Nice work!

fingers crossed it's not too much juice for those little motors.

ph2t · Post by **ph2t** » Thu May 17, 2007 5:14 pm

Good point. I held it in my hand (the motor that is...) for a few minutes on full throttle and no real heat was generated.

I would not run the prop and tal rotor motors without their props on though. Reving it too high and you get that oscillating sound from off centre harmonics.

Interesting thing though. I but a BitCharG 3.0 motor in as the prop motor in my donor/practive piccoz and it would cut out after a few seconds. It appears that there is a current limiting aspect to the circuit.

Also, there is a small PCB on the lipo. Possibly the lipo charger or overcharhe / over discharge (<3.0V) protection circuit. I tested the Bit 3.0 motor on both a regular lipo and the lipo without the PCB and both times it cut out. So it's gotta be on the main PCB somewhere.

crazydave · Post by **crazydave** » Thu May 17, 2007 11:36 pm

Don't know crap about heli's but I know that the Tomy 3.0s are current hogs. Alot of clone motors were round about 3.0 and had good torque, got any of those left laying around?

ph2t · Post by **ph2t** » Thu May 17, 2007 11:54 pm

nah, but I got some 1.0's and 1.6's, they may better suited for 3.6V. the stock rotor motor is a longer can though (by 1-2mm) and it feels like it has a fair bit or torque.

I've run it for a while today and here's the things I've noticed.

-I can run now at a lower speed but hold the same altitude.

-I only need to trim right 1-2 times. previously I had to do up to 6-8 times for right.

-The "angry stage" of the first few minutes of flight is a lot calmer now. since I can now run at a lower throttle, it smooths out the flight a bit.

-It climbs like a muthafucker.

way faster.

-the extra oompf in the tail rotor definately helps with trim. bigtime. specially when you adjust it during flight as all picco-z users well know

gonna take it for a run soon in a big sports hall, I'll try and get a good figure for overall runtime.

has anyone put larger capacity lipos in this thing? I guess you would have to balance it a bit and the net weight increase may kill any improvements but I gotta get longer freakin runtimes.

Is the stock lipo 80mah? or 50mah? confused......

Clint · Post by **Clint** » Fri May 18, 2007 1:14 am

Rock on. You sold me on this mod. I hate having to trim it 100 times during flight.

I guess it's time to order some phets.

stock is a 50mah.

Clint · Post by **Clint** » Wed Jun 13, 2007 1:15 am

finally got around to ordering a batch of these mosfets.
they are real cheap, so i grabbed 20 of them.

if anyone else wants to do this mod, lemme know and i'll drop a set in the mail. *FREE*

betty.k · Post by **betty.k** » Sun Jul 01, 2007 3:08 am

i wasn't gonna bother with a picooz but a couple of weeks ago ph2t comes over and says "happy early birthday cockfag!!"

so i flew it stock a couple of times then fetted the tail motor.
it was really good, once you get used to it and the tail response and hold was pretty good. i would have to trim it often during a flight as i needed more throttle to keep it up as the battery flattened.

i then swapped out the main motor fet. i noticed the tail was weaker again and i only need to use the first 2 steps of throttle during the whole pack.

runtime seems to be a little better but i haven't tested it properly.

over all i'd recommend swapping the tail motor fet only, i thought it had better rudder control.

frizzen · Post by **frizzen** » Mon Jul 30, 2007 2:33 pm

Hey clint, is the mosfet offer still good?

Not having to trim mine constantly might make me play with it more.

Clint · Post by **Clint** » Tue Jul 31, 2007 10:21 am

frizzen wrote:Hey clint, is the mosfet offer still good?

Not having to trim mine constantly might make me play with it more.

sure. PM me your addy.
i havent done the mod yet. i'm slacking off.

*new house - lots of work.