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Let's get started! Follow carefully. 

1. Download Simtek App 



2. Follow instructions

3. Arm your Simtek Sensor by placing in any area w/o light or motion. Automatically arms in 1-2s when no light or motion is detected. Test in shoe box or drawer first, and use wired antenna first time!

4. Triggered when light or motion is detected. First alert takes up to 10 minutes to receive; subsequent alerts between 20s - 30s. 


Read this or your Simtek Duo may not work properly!

Use the long wired external antenna for initial setup and first few alerts to ensure maximum signal as it tries to find the best network for the first time. Later, you can unplug the external antenna and it'll auto switch to an onboard internal antenna (not as good as wired).

Allow up to 10 MINUTES to receive the first alert(s), because it has to find and connect to the best network. Subsequent alerts will take 20s-30s every time and be consistent.

There is no visual indication of when Simtek Sensor is armed. You will see when it transmitting alerts by looking at the green + red LED GSM cellular modem indicator lights blinking (NOT the blue motion detection LED). The blue LED will blink when it detects any motion, regardless of if it's armed or not. If you see the blue light blink, then the red/green lights blink - it WAS armed, you TRIGGERED motion, and it's currently transmitting the alert to you! At this point, you will receive an alert within hopefully 20s and it will either go back into the arm state (if it doesn't detect light and motion) or it will stay un-armed if it keeps detecting light and motion. 

Simtek Sensors have an internal antenna, but it's not as good as the wired plugged-in antenna. 

It re-arms itselfs automatically when light or motion is no longer detected after 1-2s. If it's in a room with constant motion or light, it will never re-arm. For example, if you have it in your dark and motionless closet, and walk into the closet, you triggered the Duo by motion. And when you leave it, it will re-arm itself automatically. But, if you walked into the dark closet and triggered the Duo by motion, and then you turned on the light and left the light on - it would never re-arm until you turned off the light and left. It needs to detect zero light and motion to re-arm itself, otherwise it stays awake and will NOT trigger. This is intentional, you wouldn't want to get tons of alerts if you have the safe door open or have the Duo in a high traffic area.  

It will only send 1 alert until it can re-arm itself again. For example, you open the safe and it detects motion - one alert is sent until you close it and open it again. If you leave the door open for 1 hour, it still won't send another alert because it only will re-arm after seeing no light or motion. 

Blue LED is motion detection indicator. This is the hand-motion icon, and lights up when infrared motion is detected. 

Green + Red LEDs are the GSM cellular modem indicators that blink during alert transmission. These flicker and blink during alert transmission. Note: these are very useful to look at! After triggering, these will blink rapidly until the alert is sent over a network. When the red LED "locks" on, it successfully found and connected to a network (good sign!). If the red LED just blinks and never "locks" on this usually means no network was found and you need to use the external antenna, or move the antenna/sensor to a better signal location and try again (rare). 

Light detection has NO LED indicator. You read that correctly. We decided not to have an LED light that indicates when light is detected. We assume when you're looking at the device, light is already detected and motion is the only one that's helpful. Plus, the trigger source in the app tells you which one triggered the alert!

Using the external long antenna is highly recommended. If using inside a safe, either string the antenna outside the safe or place the long antenna near a seam, gap, hole or opening as close as you can inside the safe. Think very carefully about the best antenna placement for the best signal, and give it a test! Test a few times to make sure it works great, and you may need to move the antenna or sensor around the safe to get the best signal. We've found using the wired antenna and mounting it outside the safe or inside the safe closest to the door gap/seam works best. Many people choose to have their Duo near the safe just in the closet, being a step ahead of the safe.



The best way to setup your sensor for the first time is to download the Simtek sensors app on the Apple app store, or the Google Play store. Search for Simtek or Simtek Sensors. 

  • Scan the QR code on the bottom of your device, or enter in the unique device id in the app setup screen (unique device id is the 16 digit number located underneath the QR code).  
  • Insert battery (ensure battery is fully charged, or your sensor won't have enough juice to transmit an alert)
  • Insert antenna (we recommend attempting to send an alert with the external antenna first, which is larger and better than the internal antenna) before removing and using only the internal antenna.)  
  • Arm your sensor by placing it in a dark and motionless space. It has to be in a dark AND motionless space. For example, if you have it in the middle of your room with the lights on it will not arm itself. If you then turn off the lights in that room, it will arm only after it detects zero human or animal heat motion. The blue light with the hand motion icon lights up every time it detects motion. Note: There is NO light detection LED that lights up. So, you won't know if your space is dark enough until you try to arm it. We recommend placing it first in a space you know is extremely dark and motionless, like a table drawer, shoebox, or even the box your Simtek sensor came in! Then, when you verify you are receiving alerts and SMS, we recommend you then move it to where you want to. 
  • Always verify you are receiving alerts first. For example, when you want to take your sensor traveling to monitor your luggage, always arm and trigger your sensor in your luggage, before leaving it in there for the day. That way, you'll feel confident it's working and can trust it. 

Turning ON/OFF

    • There's no ON or OFF button. You control this by removing or inserting the battery. 

    Using the antenna(s)

    • There is an onboard internal antenna WHICH YOU CANNOT SEE! It works, just not as well as...
    • The long wired antenna is OPTIONAL, but highly recommended. This means if you take out the external antenna, your Simtek sensor will still operate normally and send alerts! However, the internal antenna is simply not as high performing but it's much smaller. 


    • The Simtek simcard is already pre-installed into the sensor. Note: it's against our TOS and policies to remove your simcard and use it for anything other than your Simtek sensor (don't remove and use in a phone, if you do this we will be alerted and take legal action when you run up a massive bill and ruin it for everyone else and make us go bankrupt!)
    • Simtek simcard can be removed and swapped, and you can use a different 3g GSM enabled (sms + data required) simcard. It's located on the back of the device, left of the antenna and is a slot that requires a paper clip or similar device. You'll use a paper clip to press the white simcard in until you hear a click, and then wiggle it out. Note: we intentionally made this a very difficult process, because we don't want people taking the simcard out (even to inspect it) because if you put it in wrong, it's hard to know and you would think the device is broken. 

    Manual Setup

    Email if you think you need to do manual setup and let us know why. This is NOT recommended and used only as a last resort if you cannot download the app for whatever reason. ***You risk major complications using this method.

    1. Locate the 16 digit device number on the bottom of your device. This is under the QR code, and is NOT to be confused with the serial number. 
    2. Open up your SMS text on your phone. 
    3. In the TO field, enter the following number +1(240)303-3852
    4. In the MESSAGE field, type Add 123456789
    5. ***NOTE: Remove the quotes from step 4, and replace 123456789 with your specific device number. It should look something like this Add 0004A30B0022D311
    6. Send the text. You will receive a confirmation text reply from our server if successfully registered. 
    7. Triple check digit by digit that you have entered the device number from step 4 correctly. 
    8. Arm and trigger your sensor to see if it worked. Alerts take between 15 seconds and up to 2 minutes the first time to get an alert. Normal operation alerts should come in 10-30 seconds or less after triggering.  

    manual registration


    • I have never received an alert, and I'm subscribed to the sensor - and I triple checked that I subscribed to the right device number! Help!

    Don't panic. Typically, there is an easy to fix here. Let's run through this checklist.

    1. Fully charge the battery using the micro USB cable. 
    2. Make sure the external antenna is plugged in (at least for debugging, it is helpful to have the best signal possible). 
    3. Re-Arm your sensor in a new location. Try placing it in a different space in the house (maybe a closet, or a drawer). And make sure it's dark and fully motionless. 
    4. Did you arm it and did it trigger correctly? You'll know when your Simtek sensor is trying to connect to the network when you see the green and red LED's lighting up on the right side, just under the blue hand motion icon. When it's successful, the two colors blink for about 15-20 seconds and the red LED stays lit for a few seconds, then they both shut off immediately after transmission. If your device can't ever find signal, the green and red LEDs blink constantly and shut off after about 2 minutes of trying to connect. This should be extremely rare. 
    5. Is the simcard inserted and did you, or someone else tamper with it? We do not recommend touching or removing the simcard we have installed, as it can affect the performance if it's not inserted correctly and fully seated. 

    I was receiving alerts, but now I'm not!

    Don't panic. Typically, there is an easy to fix here. Let's run through this checklist.

    1. Do you still have a data plan with Simtek, and your phone carrier? 
    2. Did you move your device to a new location that might not have as good signal?
    3. Did you unsubscribe from alerts and/or delete the app?
    4. Did you get a new phone?
    5. Are you able to get alerts from somewhere else with better service? 
    6. Is our service down? Check our Twitter, Facebook or Instagram or our homepage or blog (sorry, we don't know how we will communicate a situation like this yet so we want to link you everywhere).


    • Remove the battery, and keep the battery separate from any metal objects (place inside a plastic bag or something similar). 
    • Both the sensor and all accessories, including the battery can go in either carry on or checked baggage, but check your country specific laws. Our team has never had any problems traveling domestically in the USA or internationally to several countries.  


    Make sure you've tried to resolve them on your own first, as we are busy building new features, fixing things, or running the business. Often times, something simple (like battery not being charged, simcard inserted wrong, user not registered to receive alerts) is the case and is easily fixed. All of these are above. If you're still having problems, email and we'd be happy to help you! We want you to get the most out of your sensor and look forward to your feedback. 

    Check if our service is down. Check TwitterFacebook or Instagram or our homepage or blog (we haven't had this situation yet, but when we do we likely will email folks, but there is a chance we may post things in one of these places.)