Re: LF: Softrock RX divider IC problem, unexpected frequency out

[Andy Talbot <andy.g4jnt@gmail.com>]

If you only have supply of 0/5V you cannot have a negative '0' level.   

If your scope shows it, then it is possible your scope ground is not connected properly yo the -ve rail but instead to somehting further back showing a small 0.5V drop

or  teh scope needs setting up

Don't worry about it.  The wqaveform looks perfect - very nearly 1:1 square wave - its what happens when you do a design properly

Now worry about sorting out the divider.

Andy

On 31 January 2018 at 15:09, Chris Wilson <dead.fets@gmail.com> wrote:

Hello Claudio,


Thanks  Claudio,  but  how  do  I  fix this issue? I can rebuild an F1
engine, but this is outside my comfort zone :)

Wednesday, January 31, 2018, 2:34:33 PM, you wrote:

>
> On Wednesday 31 January 2018 11:19:51 you wrote:
>
>> I don't know I was wondering that myself. Is it significant?
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> If the HIGH level is too low the following divider can't divide properly!
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> If the LOW level can sink few mA of current from the IC  the divider can be degraded!
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> Random divide factor can be a consequence.
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> from 74HC74 data sheet, see the VIH and VIL
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> Regards
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> Claudio

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>



--
Best regards,
 Chris                            mailto:dead.fets@gmail.com