Jaume Aragay Badia wrote:

> And this other one:
> 
>                                      O +V (unregulated) being 12Vac
>                                      |
>                                      |
>                                  ----*
>                                  |   |
>                                  |   C Diode is usually 1N4001
>                                 ---  C
>                                  A   C relay coil
>                                  |   C
>                                  |   C
>                                  |   |
>                                   ---*
>                                      |
>                           1K       |/
>                PIC o-*- /\/\/\-*---|   gain>50
>                      |         |   |\
>                     +++       ---    V
>                 22K | |        A     |
>                     +++        |     |
>                      |         |     |
>                     ---       ---   ---
> 
> A couple questions on this second circuit:
> 
> 1.- Is the second diode a 1N4001?
1N4001 will work fine.

> 2.- Would a 2N2222A a good choice for the NPN transistor?
Just about any NPN will do. I have a bunch of BC337's - so I 
use them, but a 2n2222A will also work fine.
 
> The values of the DOCUMENTED relays ("n.a." was "not available", Paul) from
> FINDER I'll be using are:
> 
> 1.- For the big one, FINDER ref. # 40.52:
> 
>         Coil: 12Vdc, 220ohm, 55mA.
> 
> 2.- For the other 3 of them, FINDER ref. # 30.22:
>         Coil: 12Vdc, 360 ohm, 33mA.
> 
> Once again, Thanks for your time and patience.

These currents shouldn't pose any problem for a 2N2222A

It is a bit of overkill, but if you use it in some 
mission critical application, I'd also add a cap to 
limit the (remote-ish) possibility of a pike inducing 
the transistor to switch :

>                                             |
>                          470R     470R    |/
>                PIC o-*- /\/\/-*-/\/\/-*---|   gain>50
>                      |        |       |   |\
>                     +++       |      ---    V
>                 22K | |  10nf---      A     |
>                     +++      ---      |     |
>                      |        |       |     |
>                     -*--------*-------*-----*-


-- 
Friendly Regards          /"\
                          \ /
Tjaart van der Walt        X  ASCII RIBBON CAMPAIGN
mailto:tjaart@wasp.co.za  / \ AGAINST HTML MAIL

|--------------------------------------------------|
|                WASP International                |
|R&D Engineer : GSM peripheral services development|
|--------------------------------------------------|
|SMS mailto: tjaart@sms.wasp.co.za  (160 chars max)|
|     http://www.wasp.co.za/~tjaart/index.html     |
|Voice: +27-(0)11-622-8686  Fax: +27-(0)11-622-8973|
|          WGS-84 : 26¡10.52'S 28¡06.19'E          |
|--------------------------------------------------|