> +24v --------R--------------------------------------
> (reg?)            |        |           |
>                   |        R           |
>    (RC decouple!) |        |           E
>                   C        |---------B    fast PNP
>                   |        |           C
>                   |        R           |
>                   |        |           |
>                   |        C           R  constant current
>                   |  in- B    NPN      |   resistor
>                   |        E           |
>                   |        |           | +
>                   |        |          LED  (laser)(C?)
>                   |        |           | -
> gnd  -------------------------------------------------

Hi, what do you mean by "constant current resistor" ? Is this
a simple resistor or an active c-c, like a damn fast LM317 ?
If a simple R, then getting one with low H would be desirable

For the output pnp I was thinking along the lines of a ZTX751,
2A, 140MHz, and better for pulse switching than the normal
bipolar. Similarly something like a ZTX651 for the npn. Or do
you have "proper" HF or RF devices in mind ?

I'm very conscious of over-driving laser LEDs, they're more
sensitive than ordinary LEDs and any experimenter would
have to be quite careful. The crucial part of the circuit is the
current-limiting. Get that wrong and it's

"Welcome to Knackeredville. Population - your LED"

Vasile, what's your application ? Video link or something ?

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