The first LED is shown in the photo as a dual 7-segment display, but all HDSP-F series are single-digit displays; the HDSP-G
series are dual displays. They are also different dimensions:
HDSP-Fxxx 12.9mmH x 9.79mmW (0.51"x0.385")
HDSP-Gxxx 17.02mmH X 22.86mmW (0.67"x0.9")
Additionally, both of those displays are common anode. The board is wired for common cathode. This could be changed by reversing diodes D9 through D11, and changing the 4056 pin 6 DFI input from ground to Vdd.
Red LEDs typically have a Vf of 1.8; green has 2.1. This means different current limiting resistors could be necessary for the green displays.
The 220 Ohms for the DIP resistor and 180 Ohms for the two individual resistors were based on a Vdd of 5VDC, Vf(LED) of 1.8v and I(LED) of 15mA.
Rlimit = (Vdd - Vf(LED)) / I(LED)
Rlimit = (5 - 1.8) / 15mA
Rlimit = 3.2/0.015
Rlimit = 213.333... the closest standard value is 220.
Calculating actual current:
I(LED) = 3.2/220
I(LED) = 14.545... mA
The individual resistors are a special case, because there are diodes in the path that have a Vf drop of about 0.7.
This 0.7v drop must be subtracted from the supply voltage along with the Vf of the LED.
Rlimit = (Vdd - Vf(LED) - Vf(diode)) / I(LED)
Rlimit = (5 - 1.8 - 0.7) / 15mA
Rlimit = 2.5 / 0.015
Rlimit = 166.666... the closest standard value is 180.
Calculating actual current:
I(LED) = 2.5/180
I(LED) = 13.888... mA
You probably won't notice the difference in brightness. If you did, you could put a 3.8k resistor in parallel with the 180 Ohm resistors.
It seems to me that using two different colors of displays would make the panel look overly "busy".
It looks like the panel is about 1" or about 24mm high - what are the actual dimensions of the panel?
There is no point in proceeding if things are not going to fit.
series are dual displays. They are also different dimensions:
HDSP-Fxxx 12.9mmH x 9.79mmW (0.51"x0.385")
HDSP-Gxxx 17.02mmH X 22.86mmW (0.67"x0.9")
Additionally, both of those displays are common anode. The board is wired for common cathode. This could be changed by reversing diodes D9 through D11, and changing the 4056 pin 6 DFI input from ground to Vdd.
Red LEDs typically have a Vf of 1.8; green has 2.1. This means different current limiting resistors could be necessary for the green displays.
The 220 Ohms for the DIP resistor and 180 Ohms for the two individual resistors were based on a Vdd of 5VDC, Vf(LED) of 1.8v and I(LED) of 15mA.
Rlimit = (Vdd - Vf(LED)) / I(LED)
Rlimit = (5 - 1.8) / 15mA
Rlimit = 3.2/0.015
Rlimit = 213.333... the closest standard value is 220.
Calculating actual current:
I(LED) = 3.2/220
I(LED) = 14.545... mA
The individual resistors are a special case, because there are diodes in the path that have a Vf drop of about 0.7.
This 0.7v drop must be subtracted from the supply voltage along with the Vf of the LED.
Rlimit = (Vdd - Vf(LED) - Vf(diode)) / I(LED)
Rlimit = (5 - 1.8 - 0.7) / 15mA
Rlimit = 2.5 / 0.015
Rlimit = 166.666... the closest standard value is 180.
Calculating actual current:
I(LED) = 2.5/180
I(LED) = 13.888... mA
You probably won't notice the difference in brightness. If you did, you could put a 3.8k resistor in parallel with the 180 Ohm resistors.
It seems to me that using two different colors of displays would make the panel look overly "busy".
It looks like the panel is about 1" or about 24mm high - what are the actual dimensions of the panel?
There is no point in proceeding if things are not going to fit.
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