It's more than okay to put a zener or LED on the GND lead.
It's also okay if you don't mind blowing all kinds of current in the resistor network (the Fairchild data sheet recommends > 25mA rather than the 5mA the Poptronics circuit has), which would reduce the effect of Iq variations by about 3:1.
They also show an op-amp, but that has potential stability issues that might actually exist in the real world.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
"Spehro Pefhany" "Phil Allison"
** Completely different matter.Remaining within context is a real trial for you.
** The Poptronics abortion runs at circa 11mA. 5 / 470 = ???......... Phil
And the circuit description is demented, the output topology is not a 'voltage divider', he's putting some ridiculous amount of current through that LED, the whole thing is bad. No wonder that generation of kids just threw their hands up and quit electronics.
The pos is intractable as shown. Note that S2 is more likely a break-before-make, opening the 7805 return for even a few hundred usecs is not a good idea, output heads for the upper limits, then filtering the output with a reasonable value of capacitance is also problematic with that dammed switch too.
My context (in this thread)is hobby-level power supply circuits. Switching zeners rather than resistors is not an unreasonable approach, but we're still left with the spiking-during-switching issue.
Right, okay, bad memory, more like a 2:1 difference.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Yes, it was mentioned, you're just a little late :)
-- "I'd rather have a bottle in front of me than a frontal lobotomy" http://webpages.charter.net/jamie_5
Everyone seems to agree the schematic is a POS, any links to what more than one person believes to be a decent 5V PS?
You know, that's a good catch. Power supplies to many of us are like car's. We assume to much..
You get in your car to drive it, you shouldn't have to question if you have an engine in it! You just naturally assume that. But then again, that analogy maybe flawed if you live in a shady neighborhood :)
-- "I\'d rather have a bottle in front of me than a frontal lobotomy" http://webpages.charter.net/jamie_5
In my opinion, you would be better off with fixed post regulators of every voltage you need all branching off from the same bridge and filter cap..
If you want a variable out, you can create one from one of the higher voltage fixed post regulators with 2 Resistors and a pot.
Some Links.
-- "I'd rather have a bottle in front of me than a frontal lobotomy" http://webpages.charter.net/jamie_5
"Phil Allison"
** The following section has just been added to this popular audio design site to debunk the notion posted by Fred Abse....... Phil
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.