The common cathode LED driving circuit comprises a plurality of LED driving chips, wherein each LED driving chip is connected with a plurality of LED lamp banks anodes of all LED lamps of each LED lamp bank are respectively connected to corresponding LED driving chips cathodes of all the LED lamps of each. I think that what i have said here is all good and correct, i am tired though haha. The invention discloses a common cathode LED (light emitting diode) driving circuit. The other diode slot then could be used to accommodate something else then, maybe a resistor to control the diodes, of a low value (pF range) capacitor to smooth out the distortion, though, LEDs' tone is much rounder, softer, warmer than other diode types, so this may be an unnecessary addition to the circuit.
#Anode or cathode led for guitar pedal full
so essentially, (i guess) you can have a full LED asymmetrical setup in the space of 1 diode. i would guess that red and green being different colours, and thus different materials, renders each side of the tricolour LED a different drop voltage. So, connecting pins 1 & 3 together at the anode side of a diode's wholes on a PCB, and pin 2 at the cathode side will give you exactly the the same effect as 2 separate diodes in antiparallel, but in half the space.Īs to clipping threshholds, i am unsure. The to LEDs are in an antiparallel formation already, so can save space on the PCB.
each tricolour is made up of 2 LEDs, so you have a possibility of the two original LED colours (say, red and green), or their combined colour (in this case, yellow). You need to swap the Pnps for Npns that drive the Common Anode, Usually common Anode have pnps to drive them, common Cathode uses npns, you will also have to invert the signal to the segment drives, this can be done in software. If it is an amplifier running off +/-15v supply, then we'll talk, but for 9v floor pedals, there is simply no point in using more than one LED in either direction. The CATHODE (-) of the LED is connected to ground and our LED lights up. We supply +9v (or whatever DC voltage we are using for our effect) into a current limiting resistor which connects to the ANODE (+) of the LED. So, the upshot is that if you are using a diode complement with a VERY high total forward voltage, AND you are using a 9v supply voltage, the chances are pretty good that what you think you are hearing from use of LEDs is actually the op-amp clipping itself.with maybe a small contribution from the LEDs.Īnd that is why you only see a pair of LEDs used in floor pedals. unwired, so let’s use that to create an LED indicator.
#Anode or cathode led for guitar pedal series
If you are using a diode combination that involves two LEDs in series (e.g., a 2+1 combo for "asymmetrical"), that poses a requirement for the half-wave of the signal those diodes are supposed to clip to be at least 3v amplitude. If a pedal is powered by +9v, and the op-amp is only able to swing from 1.5 to 7.5v (a 6v, or +/-3v range), and the input signal is, let's say +/-100mv, how much gain can you apply - without any diodes whatsoever - before the op-amp itself runs out of headroom and starts clipping? Answer: 30x. cathode, such as the cold emitter, through a conducting medium to an anode.
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