Global LED brightness

[edster99]

Hi all
I'm wondering how I can recreate the functionality here where there are two options for bright (Hell) or dim (Dunkel) display. In this case the power switch is connected either direct to the circuit, or via a resistor which reduces the current to the selected incandescent bulb (see circle). As I will be using LEDs and basing my circuitry around ESP8266s, adding a resistor wont work (!)

This project has 26 LEDs which only come on individually, and I had planned to connect them to a set of 4 x 595 shift registers. Does it sound plausible to send a PWM based signal to the 595s to wind down the output brightness, or is that well outside the scope of the way a 595 would work? I can detect the power switch position easily enough so I will have a control signal in the software, but my question is : how can I use that to provide a global dimming capability across all LEDs?
Thanks

[6v6gt]

I was interested to see the the Enigma did not support digits (numbers), only 26 letters.
Anyway, you can certainly change the intensity of the display using 595 shift registers.
You could, for example, use pulse width modulation on the /OE (output enable) pins. There may, however, be better ways of achieving the same thing.
A single led driver chip such as the MAX7219 can drive up to 64 leds and permit a global intensity change.
Are all the leds the same colour/type ?

[edster99]

Yes, they are all the same type - a 1940s orange But I had another even simpler idea - after the LEDS connect to a common rail which would normally be GND, insert a switch that can either add some additional resistance to the circuit and then go to ground, or just go direct as before. Then, all the LEDS have say 220ohm, but if the switch adds an additional (single) 100ohm then the current drops some more. That can easily be built into the power switch using a 2 pole 4 way rotary... one pole connecting the additional resistor, and the other pole doing the power on/off/ external. So actually it is almost the same, it just goes on one output rather than the global input. Saves a lot of code fiddling.