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Color Bond
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Posts posted by Color Bond
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I'm a newbie, and rather than experimenting with beginner projects which serve no practical purpose once created, I'm trying to work on my own small projects which can be used for something afterwards.
For one of my first projects, I wanted to design what is basically a deluxe bleeder jumper for draining capacitors. Into a small enclosure, I'm going to use a potentiometer so that I can adjust the resistance and therefore the bleed time for any given capacitor. This way, I don't have to take 10 seconds for one and 60 seconds for another.
In addition, I wanted to set up an LED so that I would know when the capacitor was fully drained (I figure if there's not enough juice to light an LED, I'm safe). But here's where I run into my first obstacle. There is going to be a large variation in voltage and current going into the circuit - so what is the best way for me to regulate a fixed maximum voltage AND current going to the LED? (I figure it's good to end up with a max of 2 volts at 30 mA)
Doing some preliminary research, I see that there are Low Dropout Regulators which I can use to regulate voltage (I'm not saying I'm sure I know how to use them, but at least I found them! :) ), but even those allow output currents that would fry an LED. So, what is the best way to handle this? -
Thank you again, Omni and Ante, for your excellent advice. (And long posts are *always* appreciated by me, so long as it's not due to someone singing a ballad. :) )
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As far as I have learned about GFCI -
Thank you both. Knowing that GFCI doesn't cut Ground alleviates my greatest concern. I can't imagine that it's that unusual for safety to be a priority when it comes to electronics - I can't see how it *wouldn't* be an obvious concern. :)
That being said, how often is it likely that the GFCI would give nuisance trips? In other words, how often, when working with electronics, is it that people need to flow over 5 mA to Ground on purpose? -
I'm setting up an electronics workbench, and I wanted to get some expert advice as to whether I should or should not use GFCI outlets.
I plan on constructing a grounding station that would be wired into the grounding prong of a standard plug, which would be plugged in, of course. I don't know if a tripped GFCI only cuts off Hot, or if it cuts off everything including Ground. If it does cut off Ground, than I would imagine that to be a safety issue - since if I'm working on something that's powered by anything other than that outlet (i.e. batteries, a different outlet, etc...), and a problem comes up, I'm going to need that Ground for safety.
The same holds true for any self-grounding tools like soldering irons, etc...
If GFCI outlets don't cut the Ground when tripped, than that alleviates that concern, but there's still the issue of nuisance tripping - which isn't a big issue for a regular guy just using appliances, but someone working on electronics makes very active use of Grounds, and I would think it would trip often.
So, can someone experienced please chime in and tell me if I'm mistaken in my concerns and should use a GFCI outlet, or if I'm correct and therefore shouldn't?
Thanks! :)
How do I regulate voltage AND current?
in Electronic Projects Design/Ideas
Posted
I apologize for being unclear. My original idea was not to have the LED light up when the capacitor was empty, but to have it be powered by the capacitor being drained. Thus, what I would expect to see is the LED lighting up and then slowly dimming until it was off when there was no longer enough charge to sustain it.
That way, I would have a real-time indicator of the rate of drain, and this would be a completely passive device, not requiring any additional power whatsoever. If this is a viable plan, then the only issue is how to regulate the maximum voltage and current so that the charge from the capacitor doesn't fry the LED.