By Kent · Lock Depot Staff Writer

Three timers, three different jobs

Securitron sells a timer for the door that stays open too short, a timer for the door that has to do something strange in a particular order, and a timer that locks and unlocks a door by the clock. They are the TM-9, the TM-2 and the DT-7. They are not interchangeable, and picking by the lowest number on the quote is how you end up with a timer that cannot do the job. This guide separates them by what each is built for, from the listings.

The three side by side

	TM-9 Time Mate	TM-2 Time Master II	DT-7 Prime Time
What it does	Extends a momentary push or key switch	Multi-function delay and sequencing	7-day schedule
Relay	3 amp SPDT	5 amp DPDT	10 amp DPDT
Time range	2 to 36 seconds	1 to 255 seconds or minutes	12 programmed on/off times
Power	12 or 24 VDC, or 24 VAC	12 or 24 VAC or VDC	12 or 24 VAC or VDC
Set by	DIP switches	DIP switches	Digital programming

TM-9: one hand on the door, no more

This is the small one. The listing describes the TM-9 as a miniature timer that extends the hold-open request of a pushbutton or keyswitch. Think of the person carrying a box through a door with one hand free. A momentary button gives them a half second. The TM-9 stretches that to anything from 2 to 36 seconds, set on DIP switches, and its 3 amp SPDT relay energizes for that long. It fits in an outlet box alongside the button or keyswitch, which is the reason to pick it over a bigger timer: it disappears into the wall. The listing also names a second use, delaying the re-arming of alarms, and mentions shunting alarm contacts.

It runs on 12 or 24 VDC or 24 VAC. If your power is 12 VAC, the TM-9 is not your timer.

TM-2: when the door has to follow a script

The TM-2 Time Master II is the one for oddball requests. The listing gives the example of bank or ATM vaults. It takes 12 or 24 volts, AC or DC, and drives a 5 amp DPDT relay. DIP switches set the delay from 1 to 255 seconds or minutes, and it has seven operating modes:

• ON delay: the relay energizes after the delay, once the timer is powered.
• Triggered ON delay: the same, started from an external switch.
• OFF delay: the relay energizes at once and resets after the delay.
• One shot: a non-retriggerable OFF delay.
• Toggle: one closure energizes the relay and the next resets it.
• Cyclic: the relay cycles on and off at the set interval.
• Pulse output: the relay pulses for 1.4 seconds when an external switch changes state.

Triggering can come from a normally open or normally closed switch, and a flashing LED output shows the time remaining. That is a lot of capability to pay for if all you want is a longer unlock, and the TM-9 is simpler to wire. If your sequence has a step the TM-9 cannot do, this is the unit.

DT-7: the door that follows the clock

The DT-7 Prime Time is a different kind of timer. It does not run a delay when someone pushes a button; it switches things on and off at programmed times. The listing calls it a 7-day digital timer with a 10 amp DPDT relay that works in toggle or pulse mode, and it holds 12 programmed on/off times, six on and six off. Times can be set daily, on selected days or on blocks of days. Typical use: unlock the front door at opening time and lock it at close.

It has a "First Man In" feature. The listing says it delays operation until an external switch changes state, and that it automates holiday programming in many applications. In plain terms, the door does not unlock on schedule until somebody with a key or card has actually come in first. That is a decent guard against an unlocked door on a morning when nobody is there. An AA battery backs up the program memory of the display module, so a power blip does not lose the schedule.

How to choose

• The user needs more time to pass through: TM-9.
• The door needs a delay or sequence the TM-9 cannot do: TM-2.
• The door must lock and unlock on a schedule: DT-7.

Two checks apply to all three. First, match the supply voltage: the TM-9 does not list 12 VAC, the other two do. Second, size the relay to the load. A 3 amp relay is not the right place to hang a heavy lock directly; if the draw is close to the rating, use a relay or power supply built for it. We cover the lock side in the guide on matching a Securitron maglock to the door.

The timer only extends or schedules a release. It does not replace a delayed-egress timer, which is a separate device with its own release rules. That is the territory of the XDT timers. Any delayed-egress or maglock arrangement has to meet your local egress and fire rules, and I cannot tell you from a listing that it does. If you are building a keyswitch circuit around a timer, see the MK and MKA keyswitches. The full Securitron line is on the manufacturer page.

Common questions

What does the Securitron TM-9 do?

It extends the hold-open request of a pushbutton or keyswitch. Its 3 amp SPDT relay energizes for 2 to 36 seconds, set on DIP switches.

Which Securitron timer has the most operating modes?

The TM-2 Time Master II, with seven: ON delay, triggered ON delay, OFF delay, one shot, toggle, cyclic and pulse output.

Can a Securitron timer lock a door on a schedule?

Yes, the DT-7 Prime Time. It is a 7-day digital timer with 12 programmed on/off times and a 10 amp DPDT relay.

What voltage do these timers run on?

The TM-9 runs on 12 or 24 VDC or 24 VAC. The TM-2 and DT-7 run on 12 or 24 volts, AC or DC.

What is First Man In on the DT-7?

A feature that delays the scheduled operation until an external switch changes state, so the door stays secured until someone actually arrives.