Remote Adjustable Time Delay

Alternating Relays


How can I set the time delay remotely, either adjustable or fixed?


There may be an application requiring the setting of the time delay “remotely” or at some distance from the time delay relay itself. For example, the requirement may call for an adjustment outside the control panel on the front door instead of opening the door and reaching in to adjust an onboard potentiometer. Or it could require a fixed delay that may require different values for different applications as necessary. This requires a time delay relay to be built with two terminals for connection to a separate potentiometer for remote adjustment of the time delay or a resistor for setting a fixed delay. The product does not come with an onboard potentiometer-the potentiometer or resistor used with the two extra terminals is supplied by the customer. This allows the customer to select their own potentiometer with mounting, knob style and markings appropriate for their particular application.

Macromatic can build our THL, THR & THS Series encapsulated and TR-5 Series plug-in time delay relays with either of the three options above. The following discussion pertains to ordering & installing of time delay relays with remote time delay.

To order any of these products with remote time delay, either adjustable or fixed, the appropriate “-Rx” suffix is applied to the end of the catalog number. When ordered with an “-Rx” suffix, the product will come with two dedicated terminals for connecting either a remote potentiometer for adjustable time delay or resistor for setting a fixed delay.

NOTE the following important points to remember:

  • Not every function & output configuration is available with remote time delay. Either use our online Product Builder or contact Macromatic Technical Support to learn more.
  • Macromatic does not have a set-up charge for products with remote time delays but do have a minimum order requirement of five (5) pieces per catalog number. These products are available with standard lead-times. See the appropriate Product Catalog Page or call us for more information.


To use a time delay relay in remote adjustable applications, the unit must be built to match the value of the remote potentiometer. In other words, the value of the remote potentiometer must be known when ordering a time delay relay built for remote adjustment in order to have a unit that will provide the exact & full range of the relay. To order a time delay relay built specifically for remote adjustable time delay, the correct “Rx” suffix from the table below must be added to the end of the Macromatic catalog number based on the specific Series:

Circular socket diagram with little circles inside

A TR-50222-05R5 is a plug-in On Delay unit with two terminals (see diagram at right) provided for a remote 500K potentiometer. This will provide the full 0.1-10 Second range which can be adjusted remotely with the potentiometer. No onboard potentiometer is provided with the time delay relay. To order a time delay relay built to work with other potentiometer values, please contact Macromatic Technical Support. NOTE: A time delay relay that normally comes with 8 pins will now have 11 pins to accommodate the two terminals for remote delay connection, and therefore, will require an 11 pin socket.

For example, assume you want to select a resistor to get a fixed 5 second delay on a THR Series encapsulated time delay relay. Order a product with a 0.1-10 Second Delay and calculate the value of the required resistor as shown below (wiring diagram is shown at below):

Wire box diagram

Note that the same product can be used with other resistor values to get any fixed time delay within the 0.1-10 Second time range of the unit by simply recalculating the required R value. Calculated fixed resistance values are approximate only and may require adjustment for increased accuracy.


There are several considerations to be made when using a time delay relay with a remote delay:

  • Wiring used with remote time delay, either adjustable or fixed, can be highly sensitive to noise. Therefore, length of the run should be limited. Also, you should route the wires away from high power equipment. It should not be placed in conduit or a wire tray with any high voltage/current cables.
  • Remote potentiometers should be mounted in such a way as to limit or prevent ESD (static) from conducting into the time delay relay. Although the Macromatic product has built in ESD protection, repetitive shocks over the life of the product can ultimately result in damage.
  • Connecting a potentiometer or resistor with a value higher than what is shown above will NOT result in a time delay longer than the maximum of the time range.
  • Depending on the tolerance specification of your potentiometer, you may not get the full range of the time delay. If you use a 500K potentiometer with a +20% tolerance, your potentiometer may only have a maximum resistance of 400K ohms. This could result in up to a 20% reduction of the full timing range.
  • Since only two terminals are provided on the time delay relay for a remote potentiometer, you will use only two of the three potentiometer terminals–use the center wiper terminal along with your choice of either outside terminals–which terminal you select controls the direction of potentiometer rotation that increases the time delay.
  • Potentiometers are subject to “drift” or change in resistance over time as well as other environmental effects due to the way they are constructed. This drift will have an impact on the resulting time delay and should be considered.
  • Fixed resistor calculations are for reference only and subject to all applicable tolerances; Macromatic always suggests testing the fixed resistor-timer combination for accuracy or requesting a factory fixed product for best results.