Okay, so I bought a 2 lead bi-color led, but my application requires a
3 lead shared anode led. Is there any circuit I can build that would detect the presence of negative to reverse the polarity automatically
Is this a trick question? :-)
yes, install a 3 lead shared anode led is the simplest.
or get two standard LED's and hook them up as a standard 3 lead shared anode.
Don...
-- Don McKenzie E-Mail Contact Page: http://www.dontronics.com/e-mail.html Micro,TTL,USB to 1.5" color LCD http://www.dontronics.com/micro-lcd.html USB,RS232 or TTL to VGA Monitor http://www.dontronics.com/micro-vga.html World\'s smallest USB 2 TTL Conv http://www.dontronics.com/micro-usb.html
this maybe. K1 A ----|
--- Please bottom post.
There's not enough information in your post to give you actual circuit values, but here's the basic idea: (View in Courier).
| \\ | \\ IN>--+--| >O---O| >--+ | | / | / | | [R] | | | [LED] | | \\ | +-----------| >O-+ | /
"IN" is one of the signals used to drive the 3 lead LED.
If the LED's colors light up reversed, just swap the LED in the circuit.
You may be able to get rid of two of the inverters depending on what "IN" looks like. Post some more information about your circuit and you'll get more help.
-- John Fields Professional Circuit Designer
You could modify your circuit if both LEDs are *not* lighted at the same time: +--------+-----o | | + V red V gn - - | | .-. .-. | |Rred | |Rgn | | | | '-' '-' | | |/ |/ -| -| |> |>
| | === === GND GND
+---------+-----o | | + .-. .-. | |Rgn | |Rred | | | | '-'. '-' | | | red | +-+-||-+ | | gn | |/ |/ -| -| |> |>| | === === GND GND (created by AACircuit v1.28 beta 10/06/04
-- ciao Ban Apricale, Italy
"Lucky225" schreef in bericht news: snipped-for-privacy@p79g2000cwp.googlegroups.com...
As so often, it depends.
Suppose the cathodes are driven by (microcontrollers) outputs that can source and sink enough current *AND* you only need one of the colors at a time *THEN* you can simply connect the 2 lead component between the cathode cathode joints of the original LED. You may need to add a resistor to limit the current. If the outputs cannot source enough current, you need buffers. If the outputs can only sink current, you can use the upside-down circuit. See below.
CA | | C1---||---C2
Original 3 lead bi-color LED
+--->|---+ C1---+ +---C2 +---||---+ ___ C1---+ +--|___|---C2 +---||---+ | +--+ +--+ | +---| | R4___ C1--|___|--| |--|___|--C2 |\\ /| | | | | | | | +---->|---+ | +--+ +--+ | +----|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.