Which transistor?

[Alistair]

Hi,
I have a huge dilema here. Basicly its thus:

The outputs from a 4017 (5 stage Johnson Counter) are being fed into BFX 34
transistors (NPN),This part of the circuit works well. I want to drive two
12volt 21w lamps (so thats a total of 42watts and 3.5 amps of current. I
have got a TIP42A transistor that says its an PNP but it works as if its a
NPN for some peculiar reason?

Would someone out there help me find the most suitable setup for getting the
4017 to the bulbs, it is driving me nuts searching the RS website!

I drove relays from the BFX34's but with feedback, and Im limited for space
now on the second and final stage of my project, so driving the lamps using
transistors would be vey advantageous indeed.

Many many thanks

Alistair



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[Russell Powell]

Try using a power mosfets. You can easily find one that
can handle 3.5A continuous.


--
sincerely,

Russell Powell

Artisan Components
SR. FAE - U.S. Central
rpowell@artisan.com
469-438-6589





"Alistair" <alistair.echlin@btinternet.com> wrote in message
news:bm1ifa$g48$1@hercules.btinternet.com...

Hi,
I have a huge dilema here. Basicly its thus:

The outputs from a 4017 (5 stage Johnson Counter) are being fed into BFX
34
transistors (NPN),This part of the circuit works well. I want to drive
two
12volt 21w lamps (so thats a total of 42watts and 3.5 amps of current. I
have got a TIP42A transistor that says its an PNP but it works as if its a
NPN for some peculiar reason?

Would someone out there help me find the most suitable setup for getting
the
4017 to the bulbs, it is driving me nuts searching the RS website!

I drove relays from the BFX34's but with feedback, and Im limited for
space
now on the second and final stage of my project, so driving the lamps
using
transistors would be vey advantageous indeed.

Many many thanks

Alistair



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.512 / Virus Database: 306 - Release Date: 12/08/2003