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Topic: Simple programmable load (Read 17483 times) previous topic - next topic

Re: Simple programmable load

Reply #15
R4 is somewhat in flux. It could be a barrel, heat-sinked type like the itead overload, or the to-220 type like you used. Still checking parts.

I'm really only aiming for 5A of load in v1. It is just to learn the basics and maybe make a usable board. I would just live with my overload, but the LCD is shot and it barely works.

No values on many parts because it is just a circuit sketch, we still need to figure out exactly what values to use.
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Re: Simple programmable load

Reply #16
There are some mchip mcu's with "lcd driver", I never used those but with some fairly cheap lcd's floating around (100+ * 200+ pixels, some color..) it might be a good idea to use those... anyone with some experience?

Re: Simple programmable load

Reply #17
[quote author="ian"]R4 is somewhat in flux. It could be a barrel, heat-sinked type like the itead overload, or the to-220 type like you used. Still checking parts.

I'm really only aiming for 5A of load in v1. It is just to learn the basics and maybe make a usable board. I would just live with my overload, but the LCD is shot and it barely works.

No values on many parts because it is just a circuit sketch, we still need to figure out exactly what values to use.[/quote]

The only thing to watch out for would be wire-wound resistors (this seems to be the underlying composition of most "barrel" types.  Wire-wound only matter because they'll add inductance - but this only matters if you're using it dynamically.  Motor applications generally advise against wire-wound resistors for current sensing because of this.  Again, not really sure what all the possible use cases will be.  Also, if you want to pulse the FET with PWM instead of driving it linearly this additional inductance could potentially cause some issues.  I haven't designed a PWM-based load, personally, so I'm just thinking out loud here.  . .

Re: Simple programmable load

Reply #18
[quote author="arhi"]There are some mchip mcu's with "lcd driver", I never used those but with some fairly cheap lcd's floating around (100+ * 200+ pixels, some color..) it might be a good idea to use those... anyone with some experience?[/quote]
I've seen them, but that's about it.  I often wonder how specialized something like this is though - as well as how longer-term sourcing/pricing winds up comparing to "normal" MCU's - although, then again, what's "normal" mean anyway. . .

Re: Simple programmable load

Reply #19
well they are microchip so I would not worry about sourcing/pricing ... they are part of the normal pic mcu set ... I just never used them so not sure how the hack the "lcd driver" works