[sdiy] JP8 Gate circuit issue

[Phil Macphail]

> On 31 Oct 2013, at 21:31, Jack Jackson <jackdamery at hotmail.co.uk> wrote:
> 
> Hey all, I'm trying to get this gate circuit from the JP8 working. As far as I can tell you should apply 5v logic signal to the base of the transistor and it should output 15v positive gate. I can't get any change from it. I'm using correct resistor values, and a 2N3904 for the NPN. Any ideas?
> 
> http://flic.kr/p/h9o13k                 

Can you drive the input with a switch (0 & 5volts), and measure the output with a multimeter? 
It's stating the obvious but you realise that the circuit is an inverter, so for a 15volt output pulse you need an active-low input pulse?
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