Fail safe system

AJ-9000

This is the latest idea I have for a backup pump system for a liquid cooled computer, this one using two identically wired and running the same program Basic Stamps (BS-1).

Each Stamp uses;

One i/o line Hall effect sensor (coolant flow monitor).
One i/o line transistorized buffer circuit energizes latching relay wich switches power to a backup pump and turns
··· ·on a audible alarm.
One i/o line LED.
Two i/o lines for communication with the other stamp (directly wired to each other), configured as output to
······input, output to input.

Here's how it works, the Stamps monitor a impeller (coolant flow monitor) that it is turning at the right RPM's, if it isn't the relay is turned on preventing the computer from overheating.

Fail safe scenario, after a Stamp malfunctions then in the remaining good Stamp the watchdog part of the program detects that communication has stopped with the other stamp, in turn it turns on the relay and starts flashing a error code for "malfunction Stamp" on the LED.

Any thoughts about this for instance is this the right approach to do something like this ?· thankyou.

LSB

Interesting that you don't monitor the temperature of the processor directly. I can't say this is any kind of specific flaw, but it does leave the system open to failure if the fluid leaks out or, for some reason, stops circulating. Certainly the redundant BS1s and communication procedure you've described seems adiquate to me. You might, too, compare flow rate monitor readings between BS1s. It seems unneccessary, but if you have time, room... Monitoring pump temperature might warn of impending problems in time to avoid complete failure. Also, is there any "worst case senario" plan to shut down the computer?

Franklin

If this is a home style computer most of them will gracefully shutdown if you put a momentary short on the power button. This might be a first try at a shutdown before physically cutting power.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen