Adding mA meter on 50 Watt Chinese Co2 laser and controls

My machine has had one since I got it as I didn’t want to cut my laser metal work i designed a box for it to sit on top of the machine.

time to move in to a more permanent location so bye bye yellow sticker

I am now going to embed it in the metalwork of the machine with some other switches and water temp digital meter.

The Design:

I know the width of the area I am going to install this panel so in light burn I have the assets from the box I made and have imported them to the 200mm wide box. I know the dimmer switch diameter I have cloned the other switches I have coming as don’t know diameter I have a feeling they will be the same. as 16mm switches are common in automotive switches. 12v voltage 5v voltage is being used on these can be any 12v switch.

my template the small holes are for center punch metal
not enough space for the mA guage and temp gauge as want to add some labels for what they are.

I have slightly changed the original design after the first fit the gauge was too close to temperature gauge so spread it out a little more.

Test fit of all the components got to label them as well so i don’t get confused when i thread them though the machine. so time to brake up my box and remove components will test fit to template.

all fits fine.

Installing the hardware:

Time to start hole punching and drilling will do small hole first before enlarging them to appropriate sizes the mA I have a 40mm hole drill I will use. Also have scored the Rectangle for the temp gauge. will cut this out with Dremel.

I figured out when you buy a hole cutter off amazon even though it says metal cutting there not always telling the truth as blunted my 51mm hole cutter in the first 2 mins of cutting had to go to a local DIY shop to get a new one. but al cut and fitted now. just the buttons to wire and then I will then will do some cable management as gong to hardwire the air assist.

The wiring:

Thermomitor Guage:

I will use 5v form the laser power supply to power the the temperature gauge as its not used on my machine.

the ground and the +5v power the temperature gauge

I have extended the wiring as comes with 10cm of cable so have soldered and heat shrunk the connection so won’t short on anything then connect directly to the laser power supply as shown below. have hidden the wiring back in the cable tidy track

5v power output from laser power supply for temperature gauge.

the other 2 cables from the unit I have made extension leads up and extended to the water bucket and output tube.

The Dimmer switch:

in an earlier project, I installed led light tape in my machine with an external power supply and a wireless dimmer switch. it’s ok but don’t always have my phone on me to control it. When I was looking at buttons I found this dimmer switch connects to 5.5 x 2.1 connector male and female is the power in and the male goes to the led chain. As the laser does not have a 12v power supply I had a think and remembered i brought 6 x bucks convertors for a project that never happed so going to look at my parts draw as this is perfect for my needs.

What is a buck converter? well, it’s a small PCB that allows you to put 24v in one end and then adjust the output voltage with a screwdriver.

Bucks convertor

so will take the 24v from the 24v power supply through the bucks convertor which I will adjust with a multimeter to 12v this will connect with a male 5.5 x 2.1 connector which will go to the power input of the dimmer switch. i will next attach the female connector to the led wiring. lighting will only work when the laser is on.

mA meter wiring:

Wiring up the mA meter. to do this you need to find the wire coming off the low voltage end of the tube will be a thinner wire in my case was a black wire I traced it back to the power supply. I then disconnected it from the power supply and ran it to the first pin of the mA meter or the + side of the meter I then ran a wire from the other pin back to the power supply put the wire back where I had removed it. this is usually connector L on the low voltage side of the power supply. I then powered on the machine and did a test pulse and worked.

if you meter goes backward you have the wires the wrong way around,

Wiring up my illuminated buttons:

these are a 4 pin set up I run 24v in series so will power the LEDs

Now to wire up the switches, I will run a positive and ground wire from the 24v power supply. power will go in on the + then the – will come out and link to the + on the other switch then out of the – back to the power supply. as shown below in the diagram.

Switch 1 Gantry led lights:

one wire in one out wires out of the switch as illustrated below. ground will run separately to the bucks convertor this will be fed from 24v the turned down to 12v output. i might add a dimmer switch internaly if too bright.

Right switch wired now to wire up the led tap 2 solder joints later +&- then to feed the wire through the small bit of cable chain on the laser gantry then the back and forward cable chain back to wiring loom then to run it across the machine to the bucks connector I will then run the ground back to the laser power supply and the positive up to the switch and back to laser power supply 24v output.

So to start as i don’t know how much wire i am going to use i am going to work backwards i am going to solder a jst connector to led tape and to the wiring i will then thread the wire throught the machine. i have used 3m of thin gauge wire for this as have a lot of it. will cut off access cable later.

Now the wires have made it back into the control box area, I will install the bucks convertor here turn it to 12v so set ready for use. going to wire from laser PSU to bucks then feed the positive side up through the switch and back to the led positive wiring.

right all done will now test it works.

Switch2 aim assist marker on/off:

all soldiered and heat shrunk

The same principle as above but with wires taken from the 5v on the 24v supply see diagram above. i have taken the positive feed from the power supply up to switch then back to the laser marker wiring.

Now to tidy up the wiring got a load of these double-sided sticky pad wire holders from Maplin before they when bankrupt so cable ties and snips let the wire tidy commence.

all nice and tidy

Label the buttons as like to keep things tidy. Jobs is done, time to put the wire covers back on then it’s on to the next project as doing 4 projects back to back to make up for the last few months of absence.


  • 2 x bucks converters.
  • 5m of wire Red and Black live and negative.
  • 12/24v led switches.
  • Touch dimmer switch.
  • 1 x male 5.5 x 2.1 power connector screw type
  • 1 x female 5.5 x 2.1 power connector screw type.
  • 60cm 12v LED tape

Still got to add the air assist override switch but been having issues with this hence why I added a gantry light instead but this will happen after 3 days of messing I abandoned it as the led switch does not like it was causing the relay and solenoid not to close after was requried. got to dig through my parts draw and see if I can find an on/off switch to try this with will add a post once I have figured it out.

Video of it all in action:

Next Project:

Adding a 50L compressor to the air assist inline so can dual run both electric at night and the compressed air during the day. This will require some airline plumbing and re-jigging to fit it in the workshop.

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