1
\$\begingroup\$

I'd like to preface by saying k know little to nothing about electrical engineer but would like help with making a lamp. I want to use a volt meter style gauge to display a different reading for a light based on how bright it is using a dimmer switch. I'm assuming it's not as easy as simply wiring the meter to always read the current after the switch and wanted to see if anyone could help me. Any input would be appreciated.

\$\endgroup\$
  • 1
    \$\begingroup\$ In principle this is feasible. To go further we'd need some more information. What is the power source, e.g., mains voltage? What type of bulb, e.g. incandescent 100W? What type of dimmer, e.g., SCR, PWM? What safety provisions are to be incorporated, e.g., earthing? \$\endgroup\$ – Phil Freedenberg Jan 11 at 21:18
  • \$\begingroup\$ There are plenty of cheap light meters used by photographers. But I've no idea if that's okay for your use or if you really want to monitor the average current into the light (which, given the vagaries of human vision, may or may not be all that useful to you.) \$\endgroup\$ – jonk Jan 11 at 21:25
  • \$\begingroup\$ A small battery and an LDR (light dependent resistor) in series with the meter may be enough for you to make a fancy little indicator. Have a look for photography light meter apps for your phone. You might find something useful there. \$\endgroup\$ – Transistor Jan 11 at 21:58
  • \$\begingroup\$ With the correct type of meter (eg. an old-style moving iron voltemeter) it is as simple as that. \$\endgroup\$ – Wouter van Ooijen Jan 11 at 22:43
0
\$\begingroup\$

if you just want a "a different reading" depending on how the dimmer is set, just connect a simple AC voltmeter in parallel with the lamp,

With SCR type dimmers the voltmeter will not accurately track the amount of power going into the lamp but it will casnge according to the dimmer setting.

basically you put a bridge rectifier around the movement of a dc voltmeter and put a high voltage resistor in series with the input, be sure to insulate everything well.

these ones have that construction internally,

https://www.aliexpress.com/item/300V-AC/32954665170.html

With a 300V range they are well suited to 230V operation, but for lower voltages the needle won't visit most of the scale, they can however be opened and modified - eg: you could reduce the resistor to make the needle travel further

\$\endgroup\$
  • 1
    \$\begingroup\$ And even if you do track power accurately, that will not accurately predict subjective brightness, at least for incandescent bulbs. As power changes, so does the color temperature. \$\endgroup\$ – WhatRoughBeast Jan 12 at 3:04
  • \$\begingroup\$ Thanks for you input everyone. I apologize for the late response. I've been busy with training. Jasen you posted the link for a round voltmeter that would work. I don't need it to track the cottage accurately. The display is just for visual appeal, however I would perfer a rectangular one. Would this one work as we'll even if I had to open it and change the resistor to show more movement. m.aliexpress.com/item/32925975921.html \$\endgroup\$ – Nick B Feb 2 at 23:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.