Watt's This ??

[old_dude]

Hello to all those with enhanced knowledge of electronic circuitry. I've attached a PIC below. Can anyone guesstimate (or know !) what the function of this component is ???

On the far right are two MOSFETs T9018 and to their left is an LM393. Tp the left of the LM393 is a Motorola IC XFZ947. At the top of the board are the wires from a servo lead (the white "signal" lead is broken loose from the far top left corner). At the bottom are the high power connections.

I'm guessing this is an on/off switch. I've no idea how it might be connected (two red wires and one black ????) to the power source.
Any ideas will be appreciated.

Thanks
Old_dude

[pic man]

some sort of driver, let me look up the chips,
ok it looks like those two red wires are both going to the same place ( are solderd together) correct?

looks like some sorta motor controll, picture isnt too clear and when i looked up the motorola one i got nothing, my guess is lil motor driver, the larger of two wires going to dc motor the small 3 leads going into a futaba reciever,
in rc racing ones, more moffsets usually, leading me to believe its a miniture motor driver

whered u get it ?

[pic man]

that is if there connected,

perhaps theres two red one black cause of comon gorund where he cut it from,

[old_dude]

Hi PICMAN,

Thanks for the responses. Each of the three power wires has a SERMOS connector. The board itself is fairly heavy / thick I'm assuming for heat dissipation.

Old_dude

[pic man]

where the wires (red) connect to the board, is it the same contact / are they solderd together?
sermos conectors could just mean they were designed by some one with leads on there motors, here ive got a picture wich should show what i think beter then how im saying it,,

one deans connector = battery
one deans connector = motor
3 wires to speed ontroll,
extra wire is on off switch, which u dont have

now its kinda funny theres not one more wire there, but as u said , some wires have fallen off,

[old_dude]

Hi PICMAN

"where the wires (red) connect to the board, is it the same contact / are they solderd together?"

Yes, the two red wires are soldered together on the same land on the circuit board. :confused:

BTW, the only wire that was broken off was the white signal wire of the lead that would likely plug into the RC receiver.

Thanks

Old_dude

[pic man]

one thing i dont think could hurt to do ,
plug in a reciever, resolder white one and make a conector, put on 4 aa cell pack,

turn on tx and effect channle you got it pluged into,,

have a multi meter aligator'd on the black and red wires,

notate change,

did it do any thing?

[old_dude]

Yep, I'll give it a try and see what the results are.

Thanks Again

Old_dude

[Mr.RC-CAM]

My guess: Brushed motor controller with BEC and brake.

RC-CAM

[Dan Baldwin]

My guess: Brushed motor controller with BEC and brake.

RC-CAM

If it is an ESC, it's missing the connection from the negative side of the motor to the drain side of the FETs. Perhaps that connection is made by screwing the lead to the tabs on the two FETs.

Dan

[Z-ANT]

This is a Jomar SM-5 esc for brushed motors. It is an analog based unit. I may still have the instructions for one of these at home, which also contained a schematic .( I am at work right now). The fets are SMP60N03s I believe, the T9018 indicates a manufacture date of 1990 week 18. The big chip is a 4066 quad cmos switch and the smaller one is a dual op amp. Lm324 maybe. It does NOT (correction) have a BEC. The circuit board is a very brittle ceramic substrate and was prone to cracking. This was the very first micro speed control.

Regards,
z-ant

[old_dude]

Thanks Z-ANT !! :)
I'll be darned ... a JOMAR ESC. :rolleyes: Still unknown is how it's to be connected to a power source and a load. It has two red (assumed pos) connected to the same land on the board and only a single black (assumed neg) wire. SO ????

I sure would appreciate any further input.

Old_dude

[pic man]

dam , so not a bad prediction from the 23 yr old self taught pic man, go me, hey ole dude, please do let me know the cause for the absence of the second negitive wire, i knew it was a driver, but that really threw me off, did it break off as i suspect, or is it wired differently, perhaps posting the schamatic would be benificial to you and me. im really confused why there wasnt a second neg ,

( i bet zant will send ya a schamatic and we can all have closer hehe)

so zant did u happen to have one of these that u reconized it, i tried to look up each chip to determine function overall and came up dry on all but 1, how were you able to be so exact, id like to oneday be as proficient as you proved your self, any usefull info is apreaciated, i mean for identifiing circuts like this, ,, once again nice work and thnx for the contribution to the comunity

[Z-ANT]

old_dude

This speed control was designed to be attached to a heat sink with screws and nuts to provide a low restance connection between the FET's drains and to provide cooling.. The negative motor terminal was attached to a wire and lug captured under one of the screws.Either of the red wires can be attached to the motor positive terminal and the other to the battery positive. There is a small square potentiometer on the board to calibrate the unit to your radio.

I looked for the schematic this morning and didn't find it. I will try some more this weekend. Joe Utasi (Jomar) had several products based on the same basic circuit I will have a diagram of at least one.


pic man

I have been involved with electric flight for 25 years or so. I have seen then all come and go. Joe Utasi published his first design in Model Builder magazine as a construction article around '83 or '84. I built several with excellent results. I also owned serveral of his other products. Once I started getting involved in larger electrics ,24 to 44 cells , I found it necessary fo me to develop my own controls. I designed my first PIC based brushed and brushless (sensored ) ESCs about 10 years ago.

Regards,
z-ant

[old_dude]

Yes...thanks Z-Ant !!

You exemplify the great depth and quality of knowledge that visits this wonderful resource .... RC Groups.

Thanks so very much.

Old_dude

p.s. Dan Baldwin.... you got the connections right !! Alas there's no prize :p