Ok.

I'm obviously, *very* rusty on my A-Level electronics.

Anywhere you suggest (perhaps a book), which'll tell me what 'open collector'
means, pull-up, pull-down and such like?

The only amplification I vaguely remember is emitter follwer...

Regards,
Mark

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu]On Behalf
> Of Russell McMahon
> Sent: 06 October 2004 14:07
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC]Voltage pull-ups for 1.5v signals?
> 
> 
> A 74HC07 is specified down to a Vcc of 2 volts.
> It  *MAY* work on 1.5v but it is very naughty to exceed data 
> sheet specs :-(
> 
> If it did work it would do what you want with pullup 
> resistors to 5v on the 
> outputs.
> 
> An LM339 quad comparator running on 5v would work well. (Jinx 
> suggested a 
> comparator). An LM324 opamp would be OK but the positive 
> voltage swing would 
> be somewhat wimpy - but you'd save 4 resistors.
> 
> In each case join all inverting inputs together and connect 
> to about 0.8vdc.
> Drive non-inverting inputs from input IC and outputs go to PIC pins.
> 
> LM324 may be helped by output pullup resistors (irregular). 
> LM339 must have 
> them as it is open collector.
> 
> 
>         RM
> 
> 
> 
> 
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