DIY Adapter for Glass and Magnetic Scales


  • Supports four linear axis inputs, tachometer, and a touch probe or tool setter input
  • Scale inputs can be configured for use with PNP, NPN, and push/pull sensors
  • Two separate onboard linear voltage regulators provide clean power supply voltages to the 5V scale rail and 3.3V logic rail
  • Per-scale bypass capacitors filter out transient spikes on the power supply lines
Scale Inputs 4
Tachometer Input Yes
Probe/Height Setter Yes
Power Supply 7.2V DC - 9V DC
Current Draw Approx. 200 mA
Width 2.7"
Length 2.8"

Supported Scales

A typical example of glass DRO scale

This TouchDRO adapter circuit supports a wide array of Glass and Magnetic DRO scales, as well as many standard rotary encoders that output a quadrature signal with a 5V level. This includes most, if not all, brands of budget Chinese Glass and Magnetic DRO scales, as well as the vast majority of modern brand-name DRO scales.

To ensure that your particular scales are supported, please refer to their documentation to ensure that the scales use positive 5V power supply voltage and output quadrature signal with a 5V level.

For more information about Glass and Magnetic DRO scales, refer to the pages linked below:

Circuit Schematic

Circuit Schematic

Bill of Materials

Value Description Qty. Reference
MSP430G2553 16-Bit mixed-signal microcontroller (pre-programmed) 1 U1
74xx244 SN74HC244 Octal Buffer 1 U1
HC-05 Bluetooth Transceiver, Slave 1 HC-05
LM1117T-3.3 Voltage Regulator, 3.3V 800 mA, LDO 1 LM1117
LM1117T-5.0 Voltage Regulator, 5.0V 800 mA, LDO 1 LM1117
Capacitor, 100 uF Cap. electrolytic, 100uF, 35V 3 C1, C2, C3
Capacitor, 0.1uF Cap. ceramic, 0.1uF 50V 12 C4-C15
Resistor, 330 Ohm Metal film resistor, 330 Ohm, 1/4W, 5% 2 R2, R3
Resistor 47KOhm Metal film resistor, 47 KOhm, 1/4W, 5% 1 R1
Resistor Network Resistor Network, 47KOhm, 10 Pin 1 RN1
LED LED, Green 3mm, 20 mA 2 HB, PWR
Pin Header Pin Header, 4x1, 1" spacing 5 X,Y,Z,W, HC-05 (optional)
Scale Connector D-Sub 9 Pin, Female, Panel Mount 4 N/A
Power Jack 2.1x5.5 mm power input jack, PCB mount 1 Pwr

Useful Resources