Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Organ Cue Light

Not open for further replies.


New Member
Greetings to all!

I am an 'newbie' to this forum and would like to request some assistance from members more familiar with modern circuitry than myself, being an 'electro-mechanical' dinosaur from times past, and not educated in modern logic gate theory.

A brief overview of the circumstances leading to this request and the subsequent proposed ongoing solution follows. Stop me if I'm boring you...

On 14th December 2019 at 18:00hrs the Elmore Church organ in Gloucestershire, England was rendered inoperable by a local mains power transformer failure in the 11,000 volt grid distribution system supplying the church.

We are now going back in time..(ripple dissolve with upward harp glissando). In 1953 (shortly after I was born), the wind supply to the organ was converted from (choirboy) hand pumped bellows operation to a 'modern' electric blower and the hand operated pumping mechanism was completely disconnected, no doubt to the great relief of the choirboys involved..

Now back to the present day....A long rehearsed Christmas service of the 'Nine Lessons and Carols' is due to take place at 18:30hrs and is therefore in danger of being severely compromised by the absence of electrical power and hence a working wind organ.

To cut a long and possibly boring story short, the organ case was opened, the relevant hand pumping parts salvaged from beneath the organ frame and hastily re-assembled with the help of a pivot pin improvised from a screwdriver donated by a member of the congregation. Time, 18:35Hrs.

The service thus proceeded successfully by candlelight (fortunately pre-planned) albeit with the twin bellows operating on the single upstroke only due to a lack of linkages and pins.

Needless to say, the sense of triumph, euphoria and human bonding engendered amongst both congregation and conscripted 'pumpers' has welded the 'candlelight hand pumped service' into future Christmas services.

Now to the nub of the problem as experienced on the night...effective communication between the Organist and the Pumpers. When to start the team pumping, to ensure sufficient wind pressure for the next rousing chorus and when to stop the pumping, to avoid unnecessary heart attacks and hernias. Frantic and largely meaningless gestures performed in semi-darkness followed by the consequent high speed sprint across the ten yard gap between keyboard and pump lever were not the optimum solution. And although highly amusing to all those concerned (to the point of nearly suppressed hysterial laughter), the religious reverence of the service was always in danger of compromise.

Hence the following idea for the future.

A battery powered 'cue light' arrangement such that the organist can get the pumpers into action in good time, and let them 'off the hook' at the end of the hymn.

Here follows the practical solution minus the clever circuit solution, and that's over to you Guys!

So, cue light system overview:

The proposed system consists of two boxes connected by a standard 3 pin balanced audio lead (XLR-3M to XLR-3F).

Box 'A' is the master (send) unit and has a Bi-colour LED (Red/Green), a toggle switch (on/off), and contains the battery (PP9) and as yet undesigned circuit board.

Box 'B' is the slave (receive) unit and also has a Bi-colour LED (Red/Green) and a momentary push button as a 'signal acknowledged' function.

In operation, the toggle switch on the master unit turns the system on and provides immediate power to both master and slave unit LED's which are series wired (in case of circuit connection failure) and initially show RED.

When the momentary button on the slave unit is pressed, both LED's change state to show GREEN and further presses of the momentary button have no effect.

Switching OFF the master unit resets the system ready for the next power ON.

The circuit board therefore has FIVE connections.

1 - +ve via the toggle switch as power ON

2 - in RED light function +ve to LED's on both boxes

> - in GREEN light function -ve to LED's on both boxes

4 - in RED light function -ve to LED's on both boxes function

> - in GREEN light function +ve to LED's on both boxes

3 - Momentary +ve signal from slave unit to master circuit to change LED state from RED to


5 - permanent -ve

See attached circuit rough schematic for general arrangement.

(OBS- The polarity on 2 & 4 is necessarily reversed when 3 receives +ve (high) pulse from slave momentary push button)

(OBS - GREEN LED = max. wind reservoir pressure achieved..confirmed by assistant pumper with a push on the momentary button and indicated to him (/her/LGBTQ) at the pump handle by a little brass pendulum connected by string, pulley and stick to the top of the organ wind reservoir....very high tech for 1830. Thus signals a 'green light' to the organist that playing may commence at will and in confidence of fully winded success.)

Thanks to you Guys in advance for your help with this, I'm too old and bewildered to work all this out by myself.


P.S. Apologies for the scrappy circuit diagram.


  • Cue Light 02.pdf
    43.9 KB · Views: 156
Wouldn't the use of electricity for signalling ruin the spirit of the occasion? Why not supply the organist and pumpers with kerosene railway lanterns, the kind that has a green lens on one side and red on the other. To start pumping, the organist turns his/her lantern so that green is facing the pumpers. They then acknowledge by turning their lantern so that green faces the organist. At the end of the hymn, The organist rotates the lamp to red, and pumpers acknowledge by doing the same. Essentially what you have proposed, but without electricity.

Otherwise, I think you could implement your LED circuit with only the addition of a DPDT (double pole double throw) toggle switch.
Hi BobW

Thanks for your excellent alternative solution to my circuit by using lanterns, flames and kerosene, and what a great introduction to this forum!

Unfortunately the premise of your idea assumes a direct line of sight twixt the two parties involved, not to mention the current availability of suitable hardware and hydrocarbon based fossil fuel...very non PC...and anyway, where can you buy paraffin in the U.K. these days..?

Also the health and safety issues arising from the use of such technology in the hands of untrained operators in the confines of a flammable listed building could be a sticking point with the Parish Council.

Incidentally, I do have such a kerosene lantern but sadly only one, and from a goods train brake van with only one red lens so I am unable to fully test your theory.

However, it is good to see that my thread has activated a latent comedy script writer, so keep up the good work!

In the meantime we can also discount the two tin cans and length of string idea, as well as a series of pulleys and levers operating surplus railway signals, as somewhat impractical. Oh, and the DPDT toggle switch would have no auto reset function..

Looking forward to even more sensible ideas from interested parties in due course.

What is wrong with the church's electricity? Why isn't it reliable? Can't it be fixed?
People use a generator in the park, can't you?
Belated welcome to the forum. My post was only partly in jest BTW. My next suggestion was indeed going to involve ropes and pulleys, but we'll let that one go.

I had thought that since you had mentioned candlelight, then flames might be acceptable.

Sorry, I missed the need for an auto reset. I had intended that the DPDT switch would be centre off, and thought that the organist could set it to one position, wait for an acknowlegment and then release it. Trying to keep things as simple as possible. So, it looks like either a relay (or two) or digital logic will be required.
To get the bipolar drive you indicate for the LEDs, a cheap and available way is to use two bipolar 555's (*not* CMOS LMC555s). One 555 is the set-reset flipflop and output driver, and the other is an inverting driver.

Another way that is more entertaining is a single ULN2004, configured as both the flipflop and the bipolar output drive.

If AC is generated then two loops with an LED in each could be used (common return). With diodes in switch lines either end can have control over the other ends LED. Or is that getting a little complicated.

Try this - no real electronics, just based on a latching relay setup:


DC power in at the left - 9V, 12V, 24V or whatever is convenient and to suit the relay.

The left hand switch is the main off/on control.
When that is turned on it connects power to the LEDs with positive at the right side of the chain.

Pressing the right-hand button (a momentary switch) connects power to the relay coil and pulls that in.
That reverses the polarity of the supply to the LEDs, and also latches the relay in via the diode until power is switched off.

The capacitor is to ensure the relay holds in as the contacts change over & the resistor limits the initial current through the switch.

If you wanted it to work on a lower voltage (eg. 6V), the LEDs could be paralleled, each with its own resistor.
The LED resistor(s) need selecting to suit the LED current and supply voltage.

Either way there are only three wires to the right-hand section with the remote LED and button.

The cap could be 10uF - 100uF, it's not critical. The upper resistor could be eg. 10 Ohms or 1/10th the relay coil resistance, again, not critical.
The diode could be any 1N4000 series.
Thanks to everybody for your help with this, and your various suggestions which are much appreciated.
Apologies for the tardy response to your posts, no offence intended.
Thanks rjenkinsgb for your excellent circuit and the time you took to write it up. I will build and implement this in the next few weeks, life permitting.
I'll post some pictures of the finished project in due course (if the forum allows...?).
In the meantime, thanks to everybody once more.
Not open for further replies.

New Articles From Microcontroller Tips