Re: roZetta Status

[nobody@xxxxxxxxxxxx (Dave Houston)]

I agree, but given the prices folks have paid for the JDS, HomeVision, HAI,
etc. controls and given that roZetta is a DIY design, a few $0.50 cent optos
are probably worthwhile to avoid any potential problems.

"Alan Vogel" <avogel2@xxxxxxxxxxxxx> wrote:

>I'm not sure why optoisolators are necessary here.  All uPs that I'm aware
>of have proection diodes on all of their inputs.  However, these diodes are
>not beefy in terms of current handling capability.  As long as the current
>is limited to 40uA or so through a resistor, it should be no problem.
>
>Alan Vogel
>
>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:44fc6742.2111965359@xxxxxxxxxxxxxxxx
>>I don't know. The ZX-40 (nee Atmel ATMega32 AVR) and most current PICs have
>> protection diodes on input pins so I was looking to save a PL513 or TW523.
>>
>> I believe I asked whether the JDS controllers could deal with it or
>> whether
>> optos were needed and he emphatically opted for optos as a general
>> precaution.
>>
>> "Alan Vogel" <avogel2@xxxxxxxxxxxxx> wrote:
>>
>>>Just curious,
>>>
>>>What was the issue using the 12VAC xfmr?
>>>
>>>Alan Vogel
>>>
>>>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>>>news:44f43f7d.1577502015@xxxxxxxxxxxxxxxx
>>>
>>>snip
>>>
>>>>  Jeff Stein at JDS reacted in horror (well not really) when I
>>>> suggested using a 12VAC transformer to supply ZC so optos are required
>>>> between any of the controllers and the TTL port. I've designed circuits
>>>> for
>>>> both that are easily built on a general purpose board I've designed.
>>>
>>
>