Seeking miniature 240V panel indicator lamps

[Vortex5]

I am struggling to find miniature 240V indicator lamps (neon or LED) that are sufficiently small to install into a standard depth wall plate - like MK LOGIC.

All the parts available from MAPLIN are simply too long (30mm+) to be elegantly used. IDEALLY I am looking clip in lamps with integral resistor and insulated flying leads.

Any suggestions?

[BTW the application is to make a diagnostic light panel to go near my CH wiring centre so I can clearly see what is going on at any point in time with the various stats, pumps and timers etc. This will need multiple indicators.]

[dom]

A rather more expensive solution, but you could look at an MK gridswitch panel (up to 4 by4 locations I think), and the MK clip-in red neons for the gridswitch range.

[Harry Bloomfield]

Vortex5 wrote on 28/03/2010 :

Why not use LED's instead?

You could use several high value resistors and a bridge rectifier, to get an LED to operate on mains, but it would not be very efficient and would generate lots of heat. Instead the following circuit is very efficient....

Get hold of an AC mains rated 0.15uF capacitor, 1 x 0.25W 1K fuse type resistor, 4 x 1N4001 diodes or a (small diode bridge), 1x 10mA LED (colour of your choice).

___ || L-|___|--||--------------- || | | - V ^ - | LED| |->|-| - V ^ - | | N-------------------------

You may need to look at the circuit in a non- proportional font to see it as intended.

[Geo]

The only ones I found, when considering the same problem, need height or width instead of depth e.g:-

[Vortex5]

Displays nicely in "notepad". A nice idea but becomes complex when I'm potentially needing 9 indicators:

System Power Timer/Stat "call" upstairs Timer/stat "call" downstairs Hot water "call" Boiler control Boiler pump overrun Solar controller power Solar pump Solar overheat (heat dump mode)

CPC Farnell and RS have a selection of nice 240V LED panel indicators. Problem is they are at least a fiver a pop.

david

[Owain]

Shouldn't be too difficult to replicate it x 9 on a PCB with some screw terminals for the mains wiring, put it in an enclosure near the CH gubbins, and extend low voltage wires to the LED panel.

Otherwise the gridswitch solution if budget permits.

Owain

[Harry Bloomfield]

Vortex5 explained on 28/03/2010 :

Those components would work out at a bit less than half of that, but still expensive. A slightly cheaper, but much less convenient way to do it - would be to use a 9 way break before make wafer switch, to connect the one indicator to each circuit in turn to check its status.

[Vortex5]

You see as a child I enjoyed Thunderbirds (the first time round).

[John Stumbles]

Eh?

One small-signal diode (1N914 or whatever) reverse-connected across the LED should do, n'est-ce pas?

___ || L-|___|--||---------+---- || | | --- V~ LED 1N914 ^ --- | | N-------------------+----

You could wire the diodes to the LEDs as one unit and the C and R in the lead to it and stuff them all into the indicator box. The capacitors need to me mains X rated though, and they'll be the bulkiest item.

[Dave Osborne]

OK, here's a bodge. If you take a double-pole[1] illuminated rocker switch, it will have four terminals Lin, Nin, Lout and Nout. If you connect mains across Lout and Nout the integral neon will light.

So,just to be clear, you ignore Lin and Nin and the position of the switch is irrelevant. You could superglue the switch into one position to avoid confusing stupid people.

e.g.

flying leads on and use heatshrink to insulate.

Less than a quid each. :-)

You can get neon indicators to match rocker switches, but none of the usual suspects stock them any more.

Finally, be aware that neons will illuminate on the merest hint of current, including the leakage current of solid-state relays, so be careful in your design to make sure that your neons are showing what you think they are showing ;-)

[1] You could use a single-pole three-terminal illuminated rocker, which will be Lin, Lout and N. Use Lout and N.

[David Hansen]

On Sun, 28 Mar 2010 09:23:54 +0100 someone who may be "Vortex5" wrote this:-

Grid components have already been mentioned. MK and Crabtree

make ranges. This is the quick but expensive route. Others have gone into the cheaper but slower route.

[James Salisbury]

N.B. Check that the measured voltages will be 230V and 0, a 3 way valve has a back feed on some of it's inputs for instance..

[NT]

You could buy any neon indicator and take the neon out of it if you cant find the simple flying lead with resistor types.

A single blanking plate sounds like a good way to mount them. Probably could be done with no drilling. But I bet you've got something fancier in mind :)

NT

[Vortex5]

Done my research now and I think my first effort will be to use the Maplin "snap in" neons like this:

you bend the spade terminals 90 degrees and cut off the plastic lug they project back about 25mm from the front face of an MK plate, theoretically leaving plenty of room within a 30mm surface pattress. Total budget about

15 quid.

I appreciate LED's are the 21st Century approach but don't fancy fannying about with discrete components.

D

[James Salisbury]

Sorry, you can't just snap off that plastic lug. The lug is there to provide for creapage (surface tracking) and clearance between the two lugs.. Try this instead

[Peter Parry]

I made one recently out of neons simply held in place with hotmelt adhesive. The windows were simply 4mm holes drilled and covered on the inside with thin plastic. As I had some green neons as well as the standard orange it was colour coded as well :-).

I've still got a dozen or so neons (they came out of some salvaged control boards) and 180k resistors if you would like some.

Panel mount neons such as the one on the bottom right of the page at

are widely available as well.

[Harry Bloomfield]

John Stumbles submitted this idea :

one diode could be used, but the LED would light at 50Hz rather than

100Hz.

[Vortex5]

> James

Well spotted James. These are even better for me (and cheaper):

what I wanted in the first place!

Thanks.

[Vortex5]

Thanks for the kid offer Peter, but I've just ordered some from rapid online!

[Geo]

Good find - I see they do these as well (for 50p) "MAINS NEON INDICATOR Will fit MK grids"