This is a circuit board I designed to provide power and connections to a digital ammeter for my laser cutter. The Input is 24 VDC and the Output of the circuit board is 5 VDC. There is RFI filtering to protect the input and output and a .315 amp fuse on the input.
- The digital display is an EPM-3D100AB 3-Digit 100A ammeter from www.lightobject.com.
- The WRB-2405CS-2W (EPS-2405-S-2W) DC-to-DC converter is also from www.lightobject.com.
- All other parts are from www.mouser.com.
I updated the schematic and changed the resistor on the blue LED from 75 Ohms to 100 Ohms because the blue LED was a lot brighter than the green LED.
The other 2 connections on the left of the circuit card are connected to the Output of the High Voltage RETURN coming from the Laser Tube and the High Voltage RETURN of the power supply. The reason the ammeter is connected to the output of the Laser Tube rather than the input is that the Laser Tube drops about 22 KV before it hits the ammeter. The reason for the 1kv isolation provided by DC-to-DC converter is to isolate the returns of the High Voltage Power Supply from the Low Voltage Power Supply feeding the Laser Controller and the ammeter. If you don’t isolate them there will be smoke!!!!
This is the first board that I made in the Reflow Oven shown on this site. The ferrite cores of the inductors and the large capacitors had too much thermal mass for the profile I chose so I had to complete the soldering by hand. Using the Reflow Oven for most standard ICs, resistors and components will work well. Still it was a lot of fun! www.OSHPARK.com
fabricated the core circuit boards for $5 per square inch (3 copies included). www.oshstencil.com
fabricated two stainless steel stencils for $28 delivered. Both boards and stencils are quality products.
If you have any questions, feel free to contact me (email on home page).