开云体育

Chris:

You need to be careful with most power supplies. I have great respect for
HP power supplies, but even theirs generate a wopping voltage surge the
moment they are turned-on. If I had the HP power supply connected to TTL
circuitry, the momentary voltage spike of 30 volts would certainly damage
the 5-volt integrated circuits in the test circuit. I hate having "walking
wounded" circuitry. The HP power supply even generates these spikes if the
voltage control is set for zero volts. So, the best thing to do is
power-up the bench supply and accurately set its output voltage before
attaching the test leads to your circuit.

Gary
On Dec 21, 2014 7:05 AM, "Chris Wilson chris@... [TekScopes]" <
TekScopes@...> wrote:

21/12/2014 14:59

I am pretty hopeless with, what to me, is a very complicated 7854. It
has 7A26, 7A19, 7B85 and a 7B54 plug in array. I have a venerable old
Farnell power supply that has just killed some CMOS devices. I
suspected my circuit building skills for a while, then realised one
output of this series / parallel/ independent dual output PS was
spiking over the set 5V badly. I can see from the scope display it's
going to at least 10V when the power switch for the side in use is
turned on. The othwer side of the supply does not appear to spike at
all. What I do not know how to do, assuming it's possible, is to
get a trace displayed and held, showing just how bad and how fast this
spike is. Could anyone describe in simple and detailed terms how I
might acquire a trace? Thanks. I got the scope for a song with its own
PS issues which are fixed, but it's probably a lot more sophisticated
than I will ever need, in reality!

--
Best Regards,
Chris Wilson.
mailto: chris@...