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Old 20-01-2021, 08:09 AM
SteveInNZ
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Join Date: May 2008
Location: Auckland, NZ
Posts: 239
Quote:
Originally Posted by adiastro.photo View Post
Now, what I am still not fully understand is CEM25 tech specs mentions 12V DC(9 ~ 15V), 1.5Amp as the power requirement. Whereas CEM40 and CEM26 specs both just say 12V DC, 5A. Although they actually say it only draws less than 1A when slewing. So like you said, if iOptron specifies 5A to make it easier for them on paper then I suppose in theory using a 3A power supply shouldn't be an issue.
Although I'm not sure if say the voltage drops to 10V, will the mount be damaged. Seriously I find it hard to believe that an electronic equipment manufacturer doesn't account for input voltage tolerance, but who knows.

It's not so much a case of making it easier for them on paper, it's simplifying the spec so that the user doesn't needlessly create a problem for themselves. In your example, if I were to select a 3A supply, I'd get one that I know can supply 3A continuously, over the temperature range, etc. But for all I know, you may pull a plug pack out of your bottom drawer that was originally used to power a desktop toy.

All electronic equipment is designed for a range of input voltages. If the manufacturer has specified 12V, they will have designed for 12V plus or minus some amount which varies depending on the application. IMHO, specifying an input of 12V (9-15V) is naive. Someone will try and power the mount from an inadequate 9V supply and have problems. If they used an inadequate 12V supply, it probably wouldn't drop below 9V and the user is happy.

Anyhow, the CEM25 (and I'd expect the CEM26) is well behaved if the supply drops out spec. The motor torque drops so it may start loosing steps if it's slewing. It makes a noise, but as it's a stepper motor, it does no harm. If the voltage continues to drop, it just turns off.


Steve.
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