Re: [CAD_CAM_EDM_DRO] Re: question for Mariss

JanRwl@... wrote:

>In a message dated 3/23/2003 3:45:21 PM Central Standard Time,
>mariss92705@... writes:
>
>
>
>>Math seems OK to you?
>>
>>
>>
>
>Thanks, Mariss, but I was unaware of Silicon diodes with only 0.3 drop, and
>Germanium (0.2 V) seems to have fallen from favor for such low-voltage-drop
>purposes---or, have I just gotten SO far out of touch there is no hope,
>anymore!
>
>So, there would have to be FOUR (if TINY) diodes added for this, or is a
>"bridge rectifier" with only total 0.6 V. drop available, now, in SMT
>package????????? I guess the teens into electronics, now, are
>unintimidated by all this TINY SMT stuff, and it IS beautiful to behold, but
>for us OLDE folkes, WHEW ! ! ! ! !
>
>

No, there are "AC" opto-couplers that have two LEDs connected in parallel,
with one reversed. Therefore, one will conduct on either polarity, and
light
will shine on the phototransistor. They are usually used with circuits to
detect the presence of some AC voltage, but can also be used to operate off
either polarity of DC signal. Using this type of device, there are no extra
diodes to add, and no voltage drop from the diodes. This is almost
certainly
cheaper than adding components externally.

Jon