You should use separate feedback on each fet if you're using it anywhere near their limits, the linear region of common switching fets are not well controlled so they won't share the load evenly. You're likely to get thermal runaway eventually causing a cascade failure. You can normally get away with paralleling them in switching applications since time in the linear region is negligible.
True. Perhaps my drawn circuit diagram was oversimplified but for every MOSFET a separate shunt resistor and op-amp was used. This is why I chose a quad op-amp; only four of the six MOSFETs are in use.
@@5VLogic Oh OK, that makes sense. Well hopefully useful to know for anyone wanting to build their own. At 50W, actively cooled, like you showed you'd probably get away with it anyway. Good video!
For selecting the mosfet, you want to make sure that its DC operating area graph contains inside it the power ratings (Amp and Volt consumption) you would like to use for the load, the threshold voltage is nicely under the opamp's power supply. If you don't use separate opamps to control each mosfet it is very likely that a single mosfet will absorb a majority of the load current, rather than each one sharing it equally. If you connected 4 mosfets to the 4 opamps in the package you'd likely get better current sharing. I'm not sure if you did this or not.
I'm thinking building a electronic load to test the capacity of some SLA AGM 12V batteries. I would say 10A should be the max, but up to 12A to be safe Would you have a diagram showing how to wire the 4 mosfets?
I love to see new channels in this field, so of course I have subscribed, eager to see what you have next. BUT, please plan out your presentations more, ...too much missing, and a few boo boos like 1) "any mosfet will do" - nope only logic level, 2) frying the mosfets onto the heatsink - AAAAH, watch the temperature and time limits. 3) six mosfets? Please explain, ...they cannot be used directly in parallel, which leads me finally to 4) What is the "actual" circuit schematic? Judged as it is I have to give it a "dislike", sorry :(
Very informative 👍 video
Very clear and professional!
You should use separate feedback on each fet if you're using it anywhere near their limits, the linear region of common switching fets are not well controlled so they won't share the load evenly. You're likely to get thermal runaway eventually causing a cascade failure. You can normally get away with paralleling them in switching applications since time in the linear region is negligible.
True. Perhaps my drawn circuit diagram was oversimplified but for every MOSFET a separate shunt resistor and op-amp was used. This is why I chose a quad op-amp; only four of the six MOSFETs are in use.
@@5VLogic Oh OK, that makes sense. Well hopefully useful to know for anyone wanting to build their own. At 50W, actively cooled, like you showed you'd probably get away with it anyway. Good video!
For selecting the mosfet, you want to make sure that its DC operating area graph contains inside it the power ratings (Amp and Volt consumption) you would like to use for the load, the threshold voltage is nicely under the opamp's power supply. If you don't use separate opamps to control each mosfet it is very likely that a single mosfet will absorb a majority of the load current, rather than each one sharing it equally. If you connected 4 mosfets to the 4 opamps in the package you'd likely get better current sharing. I'm not sure if you did this or not.
I'm thinking building a electronic load to test the capacity of some SLA AGM 12V batteries. I would say 10A should be the max, but up to 12A to be safe
Would you have a diagram showing how to wire the 4 mosfets?
Thanx 4 Upload👍💓⚘,What is Value Of Source Resistors?
cool project bro
did you buy analog meter from online store
if yes where?
i can't find analog meters in my area
Nice video sir like it very much. I love your content
No, you can't use any N channel MOSFET you need a logic laval MOSFET for this
voltage drop at high currents is I2R from leads.
18N60 mosfer will work?
Look easier the using 555 Ic to build a pwm for current control
Pro
I love to see new channels in this field, so of course I have subscribed, eager to see what you have next.
BUT, please plan out your presentations more, ...too much missing, and a few boo boos like 1) "any mosfet will do" - nope only logic level, 2) frying the mosfets onto the heatsink - AAAAH, watch the temperature and time limits. 3) six mosfets? Please explain, ...they cannot be used directly in parallel, which leads me finally to 4) What is the "actual" circuit schematic?
Judged as it is I have to give it a "dislike", sorry :(