On 5 Jan 2007, at 01:52, Ben Stuyts wrote:
the relays I recommended above need quite a bit of current (80 mA
each), so the transistor wasn't getting enough base drive to fully
turn on. I've lowered the base resistor from 47 k to 15 k and now it
works fine. This is with a BC337-40 transistor with a hFE of 250-600,
so if you use a transistor with lower hFE, you might need to lower
that resistor even more.
With kind regards,
Ben
> On 4 Jan 2007, at 23:00, analog hell wrote:I finally finished mine today, and it didn't work. This is because
>
>> I know this is supposed to be an easy part to find, but i'm having
>> trouble finding a relay that fits the PSU delay boards.
>>
>> I've twice ordered from UK suppliers (RS & Rapid) what I thought
>> would
>> be the correct part only to find both times they don't bloody fit!!
>>
>> Can any UK people recommend a part number that defo fits?
>
> Funny coincidence, I've been soldering together mine just tonight.
> I've used Tyco Axicom D2n relays, part# V23105-A5401-A201, which I
> got from Farnell. Farnell# is 4219582. This is a 5V relay, but other
> voltages are available too. Datasheet is here: http://www.farnell.com/
> datasheets/67728.pdf
the relays I recommended above need quite a bit of current (80 mA
each), so the transistor wasn't getting enough base drive to fully
turn on. I've lowered the base resistor from 47 k to 15 k and now it
works fine. This is with a BC337-40 transistor with a hFE of 250-600,
so if you use a transistor with lower hFE, you might need to lower
that resistor even more.
With kind regards,
Ben