TMR-04 Isolated-Ground TM Probe (ABS capsule)
Copper contacts in an ABS capsule — designed to keep the key ground off the panel.
Metal-bodied probes on this page conduct the key's ground return straight into the panel they are bolted to. This one is built differently: the copper contacts sit inside a moulded ABS capsule, so the TM ground is designed to be electrically isolated from the mounting surface. That is aimed at the ground loop you can get when a metal probe body meets a metal door, kiosk or machine panel that already shares a ground with the controller — a fault that shows up as intermittent reads nobody can reproduce on the bench. The self-aligning face guides the key onto the contact, and the M12 threaded neck fixes through the panel with a single nut.
Ordering information
| MOQ | Confirmed by model and order when quoting |
|---|---|
| Preparation time | Availability and lead time are confirmed by model and order when quoting |
| Packing | Confirm pack quantity, protection and labelling for the selected model. |
| Samples | Sample quantity, fees and shipping are confirmed for the selected model. |
| Payment | Agree payment terms and the payee in the quotation and invoice. |
| Shipping | Confirm the shipping method, cost and timing for your destination and order. |
| Customization | State ROM, colour, marking and packing needs; feasibility and cost require confirmation. |
A probe that keeps ground off the panel
This is not a cosmetic difference — it can decide whether the installation works. A metal-bodied probe such as the TMR-02 grounds itself through its fixing nut, so its installation notes warn that the panel must be non-conductive. Plenty of real doors are not: steel entrance plates, aluminium kiosks, machine enclosures, vehicle dashboards. Bolt a metal probe into one of those and the key's ground return can find a second path back to the controller, and reads may start failing in ways that look random. The ABS capsule is designed to remove that path, so consider the TMR-04 whenever you cannot be sure what the probe is being screwed into — and test a sample on your own panel and controller before ordering.
Key features
- ABS capsule electrically isolates the key ground from the mounting panel, helping avoid ground loops in metal enclosures; suited to installations where device GND and data GND must stay isolated.
- Designed to mount directly on a metal panel without additional insulation — the GND path is insulated inside the capsule; check the drawing for the supplied version.
- Chrome-plated copper contacts on an all-metal contact face — rated for over a million touch cycles; self-aligning entry guides the key.
- Copper-core lead and plastic housing parts. Cable gauge and materials: request the specification for the supplied version and confirm it in the quote.
- Ø24.01 mm face, Ø19.05 mm contact ring, 10.8 mm front depth, 22.37 mm body; M12 threaded neck with ABS fixing nut for easy installation.
- 215 mm two-wire lead with tinned ends — black GND, red DATA; TMR-04A adds a green/red dual LED on a four-core lead.
Product video
Specifications
| Chip / compatibility | Model TMR-04 · for DS1990A / TM1990A / RW1990 projects; verify the supplied key and reader versions with the target controller |
|---|---|
| Package | Chrome-plated copper contacts in a moulded ABS capsule — GND isolated from the outer case · Ø24.01 mm face, Ø19.05 mm contact ring, 10.8 mm front depth, 22.37 mm body · approx. 25 × 3 × 3 cm overall incl. lead, net weight ≈18 g |
| Mounting | Panel mount, M12 threaded neck with ABS nut — designed to fit onto metal panels without extra insulation (check on your own panel); 215 mm two-wire lead (black GND, red DATA), tinned ends, no terminal |
| Protocol | 1-Wire® |
| Operating temperature | −40 °C … +85 °C (1-Wire chip, per the original manufacturer's datasheet; confirm for the supplied version) |
| Options | TMR-04A adds a green/red dual LED on a four-core lead. Cable length, connector, capsule colour and other customization options: feasibility, MOQ and cost are confirmed in the quote. |
Product dimensions
Typical applications
Frequently asked questions
When do I need an isolated-ground probe like the TMR-04?
Typically when the probe screws into a metal surface that already shares a ground with the controller — steel doors, kiosks, machine panels, vehicle dashboards. A metal-bodied probe can create a ground loop there, which may show up as intermittent reads; the TMR-04’s ABS capsule is designed to keep the key ground off the panel.
Can it be mounted on a metal panel without extra insulation?
Extra insulation is normally not needed — the GND path is designed to be insulation-wrapped inside the capsule, so it fixes straight through the panel with the M12 neck and its ABS nut. Check on your own panel and wiring.
Is there a version with an indicator light?
Yes — the TMR-04A adds a green/red dual LED on a four-core lead while keeping the same isolated-ground capsule.
Related products
TMR-01 Copper TM Probe
Chrome-plated copper probe with pre-wired leads — the minimal front-end.
TMR-01A Copper TM Probe with Guide Ring
The TMR-01 with a polymer guide ring — the ring helps guide the key onto the contact.
TMR-02 Panel-Mount TM Probe (DS9092 format)
DS9092-format panel probe with M18×1 nut and 200 mm leads — a familiar front end for controllers.
TMR-02-4P Panel Probe with LED (DS9092L format)
The TMR-02 with a built-in LED — four wires, so the controller can light the ring on a valid read.