Product Overview
PM-328 200mV Dual-Slope ADC Voltmeter Display Module
Condition
New old stock (NOS) in unused condition. Includes front mounting bezel with threaded studs, two hex nuts, two washers, and instruction sheet. Board silkscreen reads PM328; onboard integrated circuit is marked MAXIM ICL7129ACPL 0205.
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Product Overview
Built around the Maxim ICL7129ACPL single-chip converter, the C+C PM328 digital panel meter delivers 4-1/2 digit (19,999 count) readout with 200.0 mV full-scale input sensitivity. Operating from an independent 7 to 12 VDC supply, it provides a high input impedance exceeding 100 MΩ and dual-slope integration for steady, noise-rejecting measurements. Selectable decimal points allow configuration for direct voltage, current shunts, temperature scales, or specialized process monitoring, while the included beveled front bezel and rear studs enable clean enclosure installation.
Key Features
- Maxim ICL7129ACPL 4-1/2 digit dual-slope integration ADC
- 19,999 maximum count LCD readout with 11 mm digit height
- 200.0 mV full-scale DC input sensitivity
- High input impedance rated at greater than 100 MΩ
- Automatic polarity indication and overrange warning
- Configurable decimal point positions via jumper pads
- Operates on 7 to 12 VDC (nominal 9V independent supply)
- Panel mounting bezel with rear threaded studs, nuts, and washers
Applications
- Building custom bench power supplies, battery monitors, and precision current shunt displays
- Replacing damaged or burnt-out readouts in vintage laboratory and calibration test gear
- Integrating digital voltage or current monitoring into industrial control panels and automation cabinets
- Constructing DIY instrumentation such as sensitive pyrometers, pH meters, and lux detectors
Frequently Asked Questions
Does this panel meter require an isolated power supply?
Yes. The module operates from an independent 7 to 12 VDC source, such as a 9V battery or isolated DC-DC converter. The power supply ground cannot be directly tied to the measured signal ground.
How are the decimal points selected?
Decimal point placement is configured on the rear circuit board using selectable solder jumper pads to match your chosen measurement range and scaling.
What mounting hardware is included with this meter?
The meter comes with a snap-on beveled front bezel, two rear threaded mounting studs, two hex nuts, two washers, and the original manufacturer specification sheet.
What is needed to use this meter for measuring voltages higher than 200 mV?
External scaling resistors installed at the RA and RB positions on the circuit board create a standard voltage divider network, allowing scaling to 2V, 20V, 200V, or higher DC measurement ranges.
The Maxim 7129 was the gold standard for putting honest four-and-a-half-digit precision onto a front panel without blowing the budget. Wire up your divider, trim the pot, and put that 19,999-count clarity right where you can see it.
