Electronics > Beginners
Fast updating DVM module or chipset
snoozer:
Hello,
as I had mentioned before am looking into building a linear bench PSU. I have looked at a ton of designs and suggestions on the internet and have narrowed it down now to 2 or 3 designs that look plausible and well done to me as a novice. One of them made the effort to even build their own DVM module. The reason is that off the shelf DVM have a very low conversion rate. This design is using a CA3162 chip with a conversion rate of 96Hz. I have been looking for that chip at the usual sources but it seems nobody is stocking it. I have found many people seem to use the ICL7106 in their designs but apparently that reaches nowhere near the conversion rate and I don't even find it specified in the datasheet. Other chips I looked at either don't mention conversion rate or have something like 7 Hz. The same goes for DVM modules, even the more expensive modules in the 50-70 Euro range either don't mention conversion rate or have something low like 5-7 Hz. Now I have to admit by myself I would not have given this a thought but one of the designs had its own build DVM module because of this and the Author made the effort of pointing that out and adding the diagrams. Could anyone give advise, anyone came across fast DVM modules or chips similar to the CA3162 that are no obsolete. I would prefer an off the shelf DVM module, I would not consider myself experienced enough to do a DVM from scratch.
Kind Regards
Jan P.
MosherIV:
Hi.
You will not need a conversion rate of 96Hz!
If you are just looking at the dvm, you will not be able to see changes faster the around 15Hz, you can do low frame rate video at that rate. For looking at the voltage setting or output of a psu, it may flicker and be more anoying than useful.
The 5 to 7Hz sounds fine for dvm on a psu.
Even the fastest hand held dmm just about do 7Hz.
The only reason to go faster is for logging fast Voltage changes to computer, but now you looking at data loggers or oscilloscopes.
maginnovision:
My 1242C and 1282A can both do 40 readings/s... But he's 100% right otherwise, even just a couple of updates a second is plenty fast for most cases.
ledtester:
Having >15 updates/second can be useful. Here's a comparison of the Rigol and Korad power supplies:
(Comparison starts at the 6 minute mark.)
https://youtu.be/EpIxw90Oku8&t=6m
MosherIV:
--- Quote ---Having >15 updates/second can be useful.
--- End quote ---
Ok, lets say it is down to personel preference then.
Personally, when setting up a psu, I do not find it useful if the 10mV digit is unreadable because it is flickering between 2 values.
In most cases, 10mV resolution on a psu is not used that often, it is only used when needing a precision Voltage maybe when you need a speific Voltage as an input to a circuit
If I am trying to do that, having it flicker to the point I cannot see it would piss me off >:(
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