Re: Serial cables & power supplies

Jeff Hinman (ust941@edcca4.bgl.ca.boeing.com)
Sat, 16 Nov 1996 07:31:22 -0800

> Also, how well does a 3volt plug pack work as a power supply? I'm
> currently working on a voltage regulator circuit, mainly to allow me to
> use the 12volt pack I already have (saves buying a new 3v one), but also
> 'cos I'm concerned about voltage ripple from a normal plug pack. Has
> anyone experienced any worries with ripple stressing their Ogo?

Hi Andrew.

With help from Jon Reinberg, I posted a design of my AC adapter for the Omnigo.
I'm not sure what you mean by 3volt plug pack. Is it an adapter shaped like two
AA batteries in series?

Concerning the ripple effect. Yes, there have been noted problems. I have been
in contact with an Omnigo user concerning that. She is using a PCMCIA Megahertz
modem with an AC adapter in the Omnigo and is experiencing ripple effect. If
she uses the batteries, they work for only 5 minutes (the current drain is high
at 1.2A or 1200 mA). When a 2A 3.0V Tektronics power supply is used, the Omnigo
acts weird. This is most likely due to ripple. I would suggest using the
cleanest power source you can design/buy.

I normally suggest the Radio Shack 3/6V 700mA AC/DC adapter. It is a regulated
power supply that provides "hum free" or rippleless use. If you are using a
modem or a card that causes the Ominigo power use to increase, I would suggest
using some other kind of regulated, high current supplying power source.

Jeff Hinman
ust941@edcca4.bgl.ca.boeing.com