Shopping Cart (0 Items)
Subtotal: $0.00
Your cart is empty!

Automotive Time-Delay Relay

Status: We are on vacation - Please expect up to 3-WEEK delay after receipt of order until order is shipped. We apologize for the inconvenience.


Now available: A new version of the TDR (called TDR-MF) which turns on when the trigger goes away. This can be useful if, for instance, you need something to turn on after you turn your ignition off.

Now available: A new version of the TDR (called TDR-L) which has a 30-minute maximum delay time.

Now available: A new version of the TDR (called TDR-MC) which is triggered with a momentary switch or signal, and during the turn-off delay can be canceled by pressing the switch again. Also available in long-delay version.

Now available: A new version of the TDR (called TDR-S) which starts the turn-on time delay immediately at power-on. After this, the trigger inputs will switch the connected device on and off with no delay. This is useful for motorcycles that need a delay on start-up, but afterwards need to be able to switch between low and high beams with no delay.


Variants


Example Applications


For sale here is a compact solid-state 12V relay with adjustable turn-on and turn-off times, and two separate inputs. It is useful for many automotive applications, including H4/9007 HID retrofit systems and motorcycle HID retrofits, but it is also useful any place you would like to add a delayed relay in your vehicle, such as for powering your car windows for a short period after turning off your car. Remember, this relay isn't only useful for the applications listed above, it can be used for many different things.

This relay has the following features:

  • Adjustable turn-on delay (0 - 120 seconds)
  • Adjustable turn-off delay (0 - 120 seconds)
  • Can be triggered by positive or negative (ground) signal, selected by polarity switch
  • Dual isolated inputs
  • Simple 0.25" spade connectors
  • Solid-state operation for high reliability
  • Compact size: 2.375" x 1.61" x 0.81" (60 x 41 x 21 mm), or
    1.53" x 1.61" x 0.81" (39 x 41 x 21 mm) without the mounting ears
  • 10A maximum continuous load
  • 3mA standby current consumption (4.5mA for TDR-P* models)

In addition, when used for headlights, this relay eliminates the need to determine if your car's headlights use positive or negative switching, as it can handle both. If your headlights (or other item) do not turn on when you turn the switch on, just flip the polarity switch.

Time-Delay Relay
Time-Delay Relays
Time-Delay Relay Adjustments
Time-Delay Relay Adjustments

Specifications
This relay comes in a small plastic box with two mounting holes, and 5 standard spade connectors on the bottom. The electronics inside are encapsulated, or potted, in epoxy and are water resistant. There are two small adjustment knobs on the back to adjust the turn-on and turn-off delays. The five connections are:

  • +12V from battery (an inline fuse is required)
  • Ground
  • Load - to be connected to the ground connection of the device to be switched (TDR), or to positive connection of device if using positive-switching TDR-P
  • 1 & 2 - trigger inputs, to be connected to signals used for switching relay on and off
This relay is rated for a maximum current of 20A peak, and 10A continuous. A typical HID ballast uses around 6A at start-up, and settles to around 3A after a few seconds, so two ballasts are well within the power limits of this relay.

There are two versions of every TDR model. The standard TDR only switches the low side, meaning it switches the ground connection of the device (HID ballast or other), while the positive connection stays connected to battery voltage. The positive-switching version of the TDR (called TDR-P) switches the high side, or positive side. Some applications cannot use the negative-switching scheme, so the TDR-P exists for customers who need positive or high-side switching, or find it more convenient for wiring.

Note that these relays are NOT waterproof. Because the connectors are standard spade terminals, which are exposed to the elements, too much water will cause them to short out; this is only preventable by using waterproof connectors. So be sure to mount these relays in a place where they will not get too wet, or be submerged. High up in the engine compartment, with the connectors pointing down and the back of the relay against sheetmetal, is generally safe, but if you wash your engine, be sure to disconnect the battery power and allow everything to dry before reconnecting the battery.

A packet of 5 matching terminals is included with each relay.

Time-Delay Relay Connections
TDR Time-Delay Relay Connections
Time-Delay Relay Connections
TDR-P Time-Delay Relay Connections
Time-Delay Relay Connections
Time-Delay Relay Connections

Triggering vs. Switching
One confusing issue with these relays is positive vs. negative switching and triggering. While these relays can use both positive AND negative triggering, they can only do positive OR negative switching: you must order the correct kind for your application. For the purposes of this write-up, "triggering" and "switching" are two different things.

"Triggering" is how the relay is activated, or triggered. When the relay receives a trigger signal on one of its two trigger inputs, it turns on after the time-delay. This trigger signal can either be positive, meaning a +12V signal, or negative, meaning a ground signal. The ability for the TDR to recognize either type of signal is useful because, for instance with headlight systems, some cars switch +12V to the headlights to turn them on and off, while other cars switch the ground side.

"Switching" refers to how the relay switches power to whatever device is connected to it. The standard negative-switching TDR switches the ground side of a device, so +12V power must be always connected to it, and the TDR switches the ground side on and off. The positive-switching TDR-P, on the other hand, switches the positive side of a device, supplying +12V, while the ground connection is always connected to ground.

While it would be nice if the TDR could do both positive and negative switching, it's not technically feasible, so there are positive and negative versions of every TDR variant. Please be sure to order the correct kind after reading through the instructions and examples here.

How many?
Should you order one or two relays? That's something every customer will have to decide for him or herself. These relays can handle the power consumption of two 35W HID ballasts, so if you wish to use one relay for your whole headlight system, it will work just fine. Of course, if you have a motorcycle with only one ballast, only one relay is needed.

However, if you have two ballasts and desire maximum redundancy, you can use two relays, with two separate fuses, so that if one ballast or relay malfunctions, you still have one headlight functional. It is also possible to use one relay with two fuses, between the relay and the ballasts, to protect against ballast failure, though you will still lose both headlights if the relay fails (not likely, but it's important to be aware of all possibilities when planning a system for maximum reliability).

Please also see the Installation Instructions page for sample wiring diagrams showing how this relay can be installed in a typical car.

Pricing
The price for either the negative-switching Time-Delay Relay (TDR) or positive-switching TDR-P is $29, plus any applicable shipping charges. When you purchase using the Paypal checkout, it will calculate your shipping cost and should give you multiple options for shipping.

Ordering
Interested? You can order one or a pair quickly and easily by clicking on one of the buttons below. Feel free to add more products to your cart before checking out, and save with combined shipping. If you would like to pay by money order, or have some other special needs, just email us and let us know how we can help you.

Other Information



Item Added!
Positive-Switching Time-Delay Relay (TDR-P)
Price: $29
Item Added!
Negative-Switching Time-Delay Relay (TDR)
Price: $29