Re: Electronics question

[ant <blowback@xxxxxxxxx>]

Check the output of the LM7805 regulator, are you getting a stable 5v?
My
guess is your new thing can't drive enough current to power the board. I'd
hack in a wall wart and save yourself the pain of scavenged power. Or make
a
new USB one ;)



2009/6/25 Paul Gordon <paul_gordon@xxxxxxx>

> One for the electronics guru's here perhaps?
>
> I run a couple of the Quasar temp monitoring boards into my HA server.
I've
> just been trying to move them over to the new Avocent serial-over-IP
box
> that has replaced my old 8-port PCI RS232 card. - these are among the
last
> couple of devices to reconnect, I've already successfully configured 2
> Comfort UCM's and a CurrentCost...
>
> I'm not getting any data from the 3145's though, and I'm wondering if
its
> related to their use of power from the DTR line of the connected
serial
> port? Here's the circuit diagram:
> http://www.quasarelectronics.com/images/electronic-kit/3145schematic.gif
>
> I've put a meter across the DTR & GND pins on the RJ45 outlet
jacks on the
> Avocent box, and I'm seeing 3.5VDC. I've also put the meter across a
couple
> of points in the 3145 board itself, and I'm seeing voltages at various
> points, - for instance, there is 0.99VDC at the DS1820 signal &
GND
> connection points, so there appears to be power to the circuit, - but
my
> question is, is it enough? - I've not yet tried to test the output
from the
> PC serial port it was previously attached to, - it's not easy to do
without
> butchering a serial cable, so I can't compare them. However, the
Quasar
> page
> for these circuits does mention the possibility of data errors due to
> unstable power from the DTR pin...
>
> I'm emailing the question directly to Quasar as well, but while I'm
waiting
> for their reply, I'd appreciate any thoughts anyone else might have...
>
> TIA
>
> Paul G...
>
>
>
>
>
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>
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