licht

Iluminating the front panels is cool. In this article the color codes are described and shows some LED driver examples.

Danger

This is a preview of the elektrophon website, the content may not be accurate and is subject to change without any notice.
LED drivers for illuminating the modules.

Danger

This is a work in progress module and might not work as expected. Feel free to file a bug report on the github page.

enlighten the front panels uses a lot of energy and cause glitches on the power rail. never the less an eluminated panel looks much better and the different types of connectors can be marked with different colors.

colortype[V]
audio signal+-5
cv signal+-5
cv pulse or gate+10
cv pulse or gate+10

the chip should be powered by +5V/GND. With higher voltage the heat dissipation will be to big and the chip will be damaged.

dc led driver

when there is a DC signal which is positive only and the signal has to be buffered the simgle transistor driver comes in handy. It is built around the common base transistor amplifier. The Led can be connected to the collector of the transisitor. The current for the LED can be set with Rx and calculated using simple ohms law.

This is the first setup with the 4069 as voltage follower. C1 and C3 are the dc blocking capacitors. When we choose R1 and R2 as 100kOhm we would excpect a gain of one.

Calculated Emitter current: 0.000608 A
Calculated Base current: 0.000094 A
Calculated current: 0.000702 A

Emitter Current: -0.000679

ac led driver

bipolar led driver

Sometimes we do not just want a light indicator for positive signals. For AC signals a bopolar LED could be used. The LED dirver has to produce positive and negative voltages.

opamp voltage: 4.999842244523887, LED: current: 5.749771253922793mA

$$ \begin{array}{c} (5V÷ 10) = RFB × 20 mA = RFB = \frac{5V)(10 mA)) = R Ω \end{array} $$
500.0
0.00043

in the simulation R2 is unchanched. For R4 the simulation is done with 100kΩ, 500kΩ, 1MΩ and 10MΩ.

references

  1. CD4069 Datasheet
  2. UBE Screamer TS-808 workalike built around the CD4049UBE logic IC
  3. WASP Filter Jürgen Haibles clone of the EDP Wasp VCF from René Schmitz.