SMS Opto Isolators.

[john stones 1 - Moderator]

Just been given a couple of these and no instructions with them, did a google and came up blank, anyone have the leaflet you could post picture of please.

[Martin Harris - Moderator]

With the magic of the Internet Wayback Machine, will this be of any use John?

 

https://web.archive.org/web/20020514095830/http://smservicesuk.co.uk/acatalog/sm33opto.html

[john stones 1 - Moderator]

Magic, thanks Martin.

[Engine Doctor]

They were great bits of kit if using 35 Meg radio with petrol engines back in the day. Haven't used mine since changing over to 2.4 . Still have two modules with fly leads. Does anyone still use them with 2.4 ?

[john stones 1 - Moderator]

I don't know ED, they came from a clubmate selling up, I recently had issues with a smaller petrol model getting glitches NGH 17, hard to get distance between ignition unit and the electrics so took these as they were free, don't know if I'll be using them yet.

[Peter Beeney]

Hi John,

 

I’m not sure if this might be any sort of clue or not, but in the past I’ve been involved in a couple of instances where there has been severe interference from the petrol engine’s CD unit on 2.4. In both cases it was the close proximity of the two batteries, ignition and radio, and in particular the two pairs of cables running partly side by side; when they were separated the interference completely disappeared.

 

Something I’ve not tried but how about a cloaking device, wrapping the batts and cables in tin foil or similar complete with a common connection to a negative; and commoning the two negative poles together at the same time might help too. 

    

Of course the simple answer might just be the opto isolator but it did seem to me to be that rather than a signal interruption type of fault it was a power problem caused by the string of inductive bumps on the radio power supply each time the capacitor was being charged up. But that really was purely speculative thinking on my part, we didn’t actually for test any of this.

 

I suspect that like 35MHz PCM radio, any 2.4 radio signal interference would not be able to get into through the radio and into the servos, in the event of total swamping the radio would just stop working and any failsafes activated would operate.  

 

Good luck.

 

PB

[john stones 1 - Moderator]

I sorted it thanks Peter, not sure how because I changed a few things, one thing I did do was move ignition unit further forward 1 inch ? Another was wrap ignition unit in ali foil, no idea if this is valid but models oven ready and not glitching.