bad batch of zero crossing optos?

dom

m s

Was it EL3033? Should have identical performance to the MOC. Maybe you got a counterfeit.

Yes, it is a EL3033 and it's possible I got a badly marked units or defective units in some why. We ordered another tube and will test one of those when they come in. We'll see where this goes.

I do remember at one time having a strange problem with a very used old coupler that was behaving much the same way. We replaced it with a zero crossing type as was the original and the problem was solved.

Might have something to do with LED emissions level internally ?

Jamie

Could the design be marginal in someway?

'Place I worked for was making a very low power battery operated product. Pullup resistors etc were very high values etc, switch on timings as short as possible etc. Some brands of components would not work in these designs.

"Dennis"

** Do you know how a zero cross, mains voltage opto works??

Hint: LED drive has nothing to do with the zero cross trick.

.... Phil

That crossed my mind how ever, units in a test jig from that same lot failed to operate as a zero crossing type and worked perfectly as a non zero type.

In many cases, the use of this lot may go on unnoticed because the side effects of not using zero crossing type most likely will not show up in many applications how ever, in this particular case, they are being used to sequence beam shift with an irradiation unit. We shift the beam between sweeps a little bit to have better coverage of the product being irradiated. Since we have 2 coils on the scan horn for this, its crucial they both sync properly, other wise, you can cause heating on the titanium window and start to generate a vacuum problem if the beam is not properly synchronized.

we use zero crossing triggers to make sure both coils start at the same time when scan is in the middle pass otherwise we get some interesting angular sweep effects.

It's now a big issue, we'll just toss these and get more :)

Jamie