I must admit that I have not had the driver board in my tiger out for a while. From what has been posted here, the driver board only has FOUR power transistors... that are all the same type? Then HenLong is NOT using an H-bridge config to drive the motors bi-directionally? Does anybody know what type of circuit configuration they (HL) are using to get bi-directional drive independantly to the two track drive motors and the turret traverse motor? I was toying with the idea of replacing the motor drives with beefed up MOSFET H-Bridges. But, if HL is not using H-Bridge config to get bi-directional control, then the MOS FET bridges wouldn't interface correctly...

Ideas??

I understand what you mean now. So is the consensus the ECG153 is the replacement to get? Aren't they like $5 each? [:'(]

I did some comparrison of characteristics of some of the power transistors listed. I do not feel that the ECG153 is really a better replacement for the 2SA1357. The ECG153 gets it's higher power rating from higher voltage ratings, not higher current ratings.
The voltage is not going to change significantly (same batt) without frying both the recvr board and the driver board.
The desire here, as I interpret it, is to run higher current, or current for a longer time without suffering heat related failure. To achieve that, I propose that you considet the NTE common characteristic replacement suggested for the 2SA1357; NTE2514. It has Higher Power dissipation rating (20W, twice) and higher max collector current rating, with other characteristics well within ball-park of the 2SA1357. Just MHO and I assume no responsibility for anyone foolish enough to follow it.

Characteristic Symbol NTE2514 2SA1357 BD178 BD436 NTE153 ECG153
Collector-Base Voltage Vcbo -60V -35V -60V -32V -90V -90V
Collector-Emitter Voltage Vceo -60V -20V -60V -32V -90V -90V
Emitter-Base Voltage Vebo -6V -8V -5V -5V -5V -5V
Collector Current DC Ic DC -8A -5A -3A -4A -4A -4A
Collector Current Pulsed Ic p -12A -8A -7A -7A
Base Current Ib -1A -1A -3A -3A
Collector Power Ta=25 C P am 1.2W 1.5W
Collector Power Tc=25 C P c 20W 10W 30W 36W 40W 40W
Junction Temp Tj 150 C 150 C 150 C 150 C 150 C 150 C
Collector Cut-off Current Icbo 1uA -100uA -100uA -100uA 20uA 20uA
Emitter Cut-off Current Iebo 1uA -100uA 1mA 1mA 10uA 10uA
Collector-Emitter Breakdown Voltage V(br) ceo 50V -20V -90V -90V
DC Current Gain hFE1 max hFE1max 240 320 250 140 200 200
DC Current Gain hFE1 min hFE1min 140 100 40 30 40 40
DC Current Gain hFE2 min hFE2min 35 70 15 40 15 15
Collector-Emitter Saturation Voltage Vce(sat) 250mV -1.0V -0.8V -0.5V -1.5V -1.5V
Base-Emitter Voltage Vbe -1.3V -1.5V -1.3V -1.1V -1.5V -1.5V
Transition Frequency fT 130MHz 170MHz 3MHz 3MHz 8MHz 8MHz
Collector Output Capacitance Cob 65pF 62pF 85pF 85pF

Nice! BUT, it doesn't have the hole in it for the heat sink. But in the pic there are two indentations in the drawing. For $1.22 each at Mouser I'd try it if you think those holes are for screws.

The RX-13 board does use a H-bridge. The other sides are in the quad array of NPN-darlington pairs in the MP4024 SIP chip, with a max rating of 3A.
Tempted to try replacing the whole lot with FETs.

D.

Swathie,

That case design is ment to use a 'squeeze fit' heat sink. Those two holes are for alignment.
Grease the back of the case with silicone heat transfer grease. for good measure, it would probablly be a good idea to use mica or thermal rubber electrical isolator. Then use a Heat sink that has a screw on spring clamp to hold the sink to the transistor.

You can make your own sink (a small binder clip, like a 'Skilcraft small hardened steel binder clip, from Office Depot, or the like, will work in a pinch) by using two strips of aluminum bar, drill screw holes on either end of the bars (beyond the area of the case contact) and sandwitch the transistor(s) between the bars. Don's forget electrical isolation (insulation) between the transistors and the sink back. And, remember that the key to a good heat sink is SURFACE AREA. You can make a really efficient sink from a strip cut from a Coke can. Cut lots of vanes and bend the first forward and the next backwards and so on (bend at about 30 degrees).
The idea is to have good heat transfre away from the device to the sink and, then, a good area of the sink for the heat to be dissipated into the air (But, when using a common sink for multiple devices, you must be carefull to electrically isolate devices from the sink).

This would all probablly make more sense with pictures, but I don't know how to do that yet.

Definitely pictures would help! It's kinda greek to me.

Thanks Darkith.

That raises all kinds of questions as to why the 1357's, but without a schematic (no I am not ready, at this point to try to reverse engineer by tracing the lands on the board), it's figure out what all is going on.....

As to replacing the whole mess with FETs, Yes MOST tempting. Two big H-bridges for the track motors, one medium H for turret traverse, and straight drive for the elevation/depression,,, or maybe since we would be scuttling the old driver anyway, servo bi-directional for main gun depression/elevation and use the cannon button to fire LED or Air soft? Would we have issues with interfacing to the recvr board? Hmmmm, maybe need to work up a PIC, or equivilent, to do mix/de-mix for steering and proportional pulse drive???? That might mean no more 'realistic Recoil' (if its realistic, why does the tank jerk back when you fire with the turret traversed right or left?).

You have already done most of this havn't you??

I came here wondering about increasing the run-time of my power source, I see there has been quite some discussion on the subject already.

Just reading this thread I have this crazy idea of attaching two slim fans under the rear engine covers, running while the tank is switched on. Would this provide enough air flow to keep the transistors cool, or is it really necessary to delve into heat sinks? Could the main drive transistors be bolted to the back of the fans with a small heat sink (like the 486 CPU one) attached to the main circuit board via fly leads with connectors in the middle for easy top hull separation?

I suppose the idea of including only a 1700 mAh battery was as much to do with cost as it was with preventing overheating, surely there should be a scientific solution possible involving air flow and heat dissipation. Anyone got a thermal imaging camera?

Jonny, if you put a fan blowing directly onto the heatsink you should be fine. I blew one transistor running Speed400s (upgraded motors) on a tank, now that the board is cooled this hasn't happened again. Lot's of pictures in my builds and others to see where the best spot is for the fan depending on the tank.

The 1357's are the P side of the bridge, the MP4024 is the N side. (4 H1357s, 4 pairs in the MP4024 = 4 bridges). I'm guessing that the MP4024 blows first due to it's lower capability and lack of heatsink.

It wouldn't be that hard to parse out the signals from the Heng Long radio and suppress the recoil (already doing both in my DBC battle circuit) and convert them, but wouldn't one of the other solutions (e.g. ELmod, Tamiya DMD, or RC radio plus 2 ESCs) make more sense for enhancing the driver board capability? I could put together a PIC that would translate the HL radio into 2 PPM signals for dual ESCs, but by the time you add that up, you might as well have bought a ELmod Booster...

Cheers,
David

I just fried two of these H1357's! The damn tank went off on demo mode and started bouncing off the walls! That's 1/2 the story. The other part is I tried installing some NiHM's 2000mAh I thought would be enough but it's not!!! I found the inrush current to be close to 4 amps!!! so I ended up replacing the NiHMs with a 12V 1.2AH Sealed Lead acid battery. Wow, does the tank ever move fast!!! So do the PNP's! I'm tempted to try some TIP's I have in my stock... or like someone else mentioned, a Mosfet H-bridge. I have to try some experiementing with some cheap H-Bridges I bought from a surplus store. I'll post my findings if anyone is interested.

What chips most commonly smoke?

Well were do I buy these transistors?


I have been searching and now I'm tired..


HELP!!!!!!!!!!![>:]

This thread has moved off from the batt capacity some what on to transistor theory!
I think the reason that the H1357's blow is because they have the PWM signal, and I could go very technical on you and explain why this could stress devices more. But I won't unless some one asks. As for a replacement I think I saw some one on a German site stuck some higher speck transistors on a bit of strip board, but for the life of me I can't find it again. I recon that adding a hand full of diodes could improve the reliability loads, along with putting a bit of aluminum plate on the outside of hull bottom coupled to the internal heatsink. By the way, the 'standard' motor requires around 9A under stall conditions with a healthy 7.2v. This could be why some failure is happening with fresh 3800mAh, and not with older 1700mAh batteries. Fresh 3800mAh will give 9A with out much volts sag, old 1700 at 9A would sag.

Any way that's my worth in this discussion.

Yours Simon M.

Well where can I order the parts is all I am asking.

My turn to be tired, I'll put it on my 'to-do' for tomorrow. Failing that I've got a duff board with some blown transistors. If I can find it do you want a good transistor from it?

Yours Simon M.

I'm trying to source the MP4104 and MP4124's and nobody seems to know what they are...


Anybody replaced their transistors with the ECG153/NTC153????

I drew out all the s&s circuits a little while ago have a look [link=http://www.rcuniverse.com/forum/m_7287428/anchors_7289704/mpage_1/key_/anchor/tm.htm#7289704]here[/link]
You can find data on them if you look on the Toshiba website The bad news is they are now obsolete, and I'm not sure if any one is doing a 'me to' replacement.

Yours Simon M.

The MP4xxx series appears to be very hard to source. I found new-old-stock MP4104s a little while back, but they were $13/ea. Hardly worth it when a full set of boards is $17 from Mato.
Haven't seen 4024s yet though.

D.

For USA or other customers that is $17 dollars, plus $ 18 dollars for shipping...... RCTankWars.com has the boards for for $30 that includes shipping, and I don't add more shipping if you want more then one board I adjust the pricing!

The Blitz
[sm=shades_smile.gif]

I recon that a 4x MJF6388 and 4x MJF6668 (10A Darlington pairs) could be pressed into service. they are current, available from [link=http://www.farnell.com/]Farnell[/link], and have an electrically isolated tab for easy heat sink attachment. Once time permits, in the next week or so I'll order some, knock up a a circuit on strip board and report back.

Yours Simon M.

Dude you are AWESOME!!!

Wait till its done, then you might call me loathsome

Yours Simon M.

You build a replacement board for these tanks..I'll buy it!!!