[sdiy] JP8 Gate circuit issue

[Jack Jackson]

Thanks, I wasn't aware - too much of a noob. I removed the R127 pullup resistor, as Tom Wiltshire suggested and then it started to output 15v on the collector as expected. 

With an active-low input, the base should be fed 5v all the time and the gate 'input pulse' would be 0v, is that correct?





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> CC: synth-diy at dropmix.xs4all.nl
> From: phil.macphail at liivatera.com
> Subject: Re: [sdiy] JP8 Gate circuit issue
> Date: Thu, 31 Oct 2013 21:55:12 +0200
> To: jackdamery at hotmail.co.uk
>
>
>
>> 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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