Driving an N channel FET? - Page 2 - Electronic Circuits Projects Diagrams Free

MikeMl · 18th August 2009, 02:11 AM

Quote:

Originally Posted by blueroomelectronics

But you still won't be able to control the flow rate. It'll be either on or off.

No, but if he turns the solenoid on for 15 seconds and then off for 45 seconds, it will deliver 25% of the flow rate compared to if were left on. As long as the cycle rate is low, this is a valid way of controlling the average flow rate.

PedroDaGr8 · 18th August 2009, 02:28 AM

Depends on what system he is working on. For example, if it is just going into a resevoir or something like that. Then hey no prob. Now if it is in an application where a constant stream is needed, just at a lower rate, then problems.

As a chemist, we encounter this situation frequently. Some reactions respond fine to say addition of 10 mL of a reagent every 15 minutes (for a total of 45 min). Other reactions may require the same amount of reagent over the same amount of time, but the reagent has to be added drop-wise, otherwise bad stuff can happen (no product, rapid boiling and in extreme cases explosions).

bigfarmerdave · 19th August 2009, 04:26 AM

I've actually done it before (PWMed a solenoid) and it works rather well to regulate oil flow. I just don't want it BANG!!! on or BANG!!! off but would rather ramp it up and down in a nice controlled manner like Smanches described.

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18th August 2009, 02:28 AM	#17
PedroDaGr8	Depends on what system he is working on. For example, if it is just going into a resevoir or something like that. Then hey no prob. Now if it is in an application where a constant stream is needed, just at a lower rate, then problems. As a chemist, we encounter this situation frequently. Some reactions respond fine to say addition of 10 mL of a reagent every 15 minutes (for a total of 45 min). Other reactions may require the same amount of reagent over the same amount of time, but the reagent has to be added drop-wise, otherwise bad stuff can happen (no product, rapid boiling and in extreme cases explosions).

19th August 2009, 04:26 AM	#18
bigfarmerdave	I've actually done it before (PWMed a solenoid) and it works rather well to regulate oil flow. I just don't want it BANG!!! on or BANG!!! off but would rather ramp it up and down in a nice controlled manner like Smanches described.