The WCA stack didn't have anything like it, but the game sometimes sticks things together. If you have a look at chapter 4, there's the description of the JP controls and that includes a magic eye indicator. It's a vacuum tube with phosphur on the end. It was put on radios in the 1930s to allow the person tuning the radio to see the relative strength of the signal he was tuining into, rather than just relying on his ears. The eye closes up and the gap between the two lit sections gets smaller the higher the voltage put into it is. The device, when attached to a gain control, as in the sonar stack, can be calibrated so that it just closes when the sound you are sweeping over is the loudest and thus get the exact bearing of the sound.
I've never seen any on radios, but I have seen one shows in a documentary about U-Boats, so the Germans probably had them too, buit I don't know for sure. When they showed the sonar operator, they showed a close up of a magic eye and I remember it clearly, as it was so striking. The magic eye looks like this:
That from a japanese website
http://www005.upp.so-net.ne.jp/y_kondo/MAGICEYE2.HTM where it looks like the guy is a collector of them.
The gap at the top gets smaller, the more voltage is fed in.
The JT sonar also had two indicators, left and right to show when the sonar was on a target. It was used when the JT head was slaved to the TDC, to show whether the bearing of the target was drawing ahead or behind the generated bearing. I'd imagine those indicators were lights, but I haven't seen anything written about that - only 'indicators'.
But, it seems that there's no way to change it in game, so I'll have to put the DCDI, DCRE and other things in the big bin of things that I can't think of a way to do.