On 07/10/11 19:01, Chuck Harris wrote:
There are lots of ways you can unintentionally affect a device
like an LPRO. For instance, suppose the internal power supply
dissipates a different amount of heat depending on the input
supply voltage. This could cause the oven to momentarily shift
its internal temperature a small amount... which may show up
as a frequency shift. Or suppose the current change due to
changing input voltage causes a magnetic disturbance that shifts
frequency?
We're time-nuts. We are trying to get more from these devices
than the manufacturer ever intended.
So you let in normal mains into you lab? >:-)
If you have linear supplies, you want to
1) Steer voltage to be within a tight spec. This will remove variation
in burned power in the linear supplies.
2) Run at higher frequency, say 400 Hz, to create smaller ripple after caps,
3) With 400 Hz the lower ripple will increase the effective voltage
after rectification and caps, so the "mains" voltage can now be reduced
resulting in even less power dissapation from the power-supply.
No, I haven't done this, but I realized this after fiddling around with
supplies and verified the ideas with a friend of mine designing supplies
all the time. He also pointed out that many switch supplies tend to run
better when the supply voltage is on the low side of things.
So, there is things to do if you really want to control your environment.
Now, how many labs log their mains voltage and correlate frequency
deviations to that?
Cheers,
Magnus
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