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Get the stuff wherever you want, I don't get anything from amazon "affiliate links"--wish I knew how to do that :-)
I have updated prices and links as of 11/11/25. Happy Singles Day!!
My "recommended system" is going to be two Hog Line "senders" and one backline "receiver" with the Xiao ESP32-C3 microcontrollers. Build two of the hog line systems and one back line system. The system is working well with these components and the 3d printed parts are easy to print and assemble. Honestly, many times I just set up with one backline and one hogline system to practice my delivery splits. I know the highest level curlers really want to know hog to hog; but the backline to hog splits are what I use to throw certain weight shots--I was taught to just let the stone go at the hogline so the first split is all I work with.
If you only want the back line to hog line "short times" and want the absolute cheapest system, then you can use a cheaper 30 pin esp32. This is what I started with so I still have the software and plastic part files available. But in order to streamline this webpage, I am taking most of the references to that off of this page. I am not sure it is worth saving $2 and having to use the older and harder to assemble cases. Any kit I send out will have the smaller xiao controllers and will be easier to wire up and put together.
NOTE: . The Xiao header pins generally need to be soldered. It's fun; but if you really don't want to solder anything, you can get the presoldered version from Seeedstudio.
Seeed studio esp32 C3 (3 pack) for $27 on Amazon. (But only about $12 at SeeedStudio and Digikey (part number 1597-102010572-ND)--stock seems to come and go with these popular chips.
An older ESP32DevKit1. 30pin version. You need 1 of these to host the webpage. Ironically, these are the chips I first used before switching to the Xiao esp32C3. Now they are back in the project to do the webpage stuff for version Larryrocktimer2.0. Get a 3 pack on amazon for about $16. But you only use 1 for each system.
https://www.amazon.com/dp/B08D5ZD528?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Laser Beam Battery Options:
Easiest is using a 3x-AA battery holder with built in switch This uses a 5volt laser. Only need to solder the two wires to the laser diode.
Five pack of battery holders for $7.99. Print the SHORT CASE for this battery option.
https://www.amazon.com/dp/B09V7VPKWC?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
A little more soldering but for the cleanest look, use a 2x-AA cell battery pack with a 3volt laser and a small switch. Print the LONG CASE for this battery option.
2 and 3 cell battery cases
https://www.aliexpress.us/item/3256806038995262.html?spm=a2g0o.order_list.order_list_main.4.584f1802kMWuyT&gatewayAdapt=glo2usa
Cheap and simple switch when using the AA battery cases.
on amazon for about .59 each. https://www.amazon.com/dp/B0CSJTHZHR?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Sensor Unit (hogline and backline) Battery Options:
The easiest system uses rechargeable phone power battery packs from walmart (see below) Just plug into the usb-c connector of the microcontroller. Simple, fast, affordable and easy.
A cleaner look uses one of the above AA-3x battery pack and small switch; but needs some more soldering.
A LiPo rechargeable battery and the same switch gives a third option. Soldering gets tricky on the new backline cases because the access to the lipo charging pads are not easy.
Here is a link to a four pack of a 3000mah 1C LiPo
Laser Diodes
My latest amazon order got 20 for $6.99. These are advertised as 3v to 5v. I think they are the same as a 5volt and work (I tested) just fine with 2x-AA cases for the 3volts. You only need 2 or 3 so share with a friend. Sometimes they aren't very focused-- you can try a different one or try rotating the outer laser beam cylinder. And sometimes they quit working so having a few spares around will guarantee that you will always be able to use a larryrocktimer whenever you want to!!
https://www.amazon.com/dp/B0FBLRQKBM?ref=ppx_yo2ov_dt_b_fed_asin_title
Straight 3volt lasers are a little harder to find. I have seen them on Amazon but I got a bunch from AliExpress. There actually is a difference between the two diodes. The small electrical component is on the anode for one and on the cathode for the other.
Here is a mixed box of each type: https://www.amazon.com/dp/B01ISVT86O?ref=ppx_yo2ov_dt_b_fed_asin_title
Phototransistor sensors. $7.19 for 3, you need 1 for the back line unit and 1 for each hog line unit.
Other light sensors would probably work just fine, but will need to have a LOW output when the laser shines on the sensor and goes to HIGH when the light beam is broken. This is somewhat counterintuitive as the LED on the sensor turns ON when the light is shining on the sensor, but the sensor output goes LOW under this condition. This sensor’s sensitivity can be adjusted by changing the potentiometer (the blue box on the top). This might need to be adjusted depending on the light intensity of the laser and the background lighting. Also note that the ESP32 is a 3.3 volt device, so the sensor needs to be able to work with 3.3 volts at Vcc. I think a simple photo detector would work and save some money but all my plastic parts are designed around this component.
(1) Infrared Sensor. $6.99 for six. Only need 1 for the sensor to arm the system.
This is used for resetting the system prior to throwing a stone. You could do the same thing with a touch sensor (original version of my system used this method) or other sensors. The IR sensor is nice because you don't need to touch the device. Simply putting a broom head near the back of the unit will prepare the device for timing. Just dont use a black glove because it won't reflect the IR light.
1.3" I2C OLED Display Now available for a 1 piece for $8.49.
https://www.amazon.com/dp/B01MRR4LVE?ref=ppx_yo2ov_dt_b_product_details&th=1
Be sure to get the 1.3" 128x64 display. I have learned that there are so many different types of these small display boards out in the world. I2C communication protocol also.
A five pack for $17.99 is a motivator to build more than 1 system and give one to a friend.
Nothing special about this display. Many other options could work. Actually, it might have some issues. The SH1306 Adafruit library does not seem to work with this display. The SH1106 library from Gyver DOES work. If you can elimate this desplay and get the data sent to your phone, then you save $8.
This is the new Walmart basic power bank. 5000mah for $7.88. The current dimensions of the hog line sensor cases don't fit this exactly, but it's not too bad.
https://www.walmart.com/ip/5K-PWR-BNK/14769668232?classType=REGULAR&athbdg=L1200
Instead of a whole case redesign, here is a simple adapter to hold this battery into the hog line case. https://drive.google.com/file/d/1qbqsBAnto2I2WRPDsJC_acvQL_irT3Gn/view?usp=sharing
Jumper wires F-F $6.98 https://www.amazon.com/EDGELEC-Breadboard-1pin-1pin-Connector-Multicolored/dp/B07GD312VG/ref=sr_1_3?keywords=f-f+jumper+wires&qid=1661307143&s=industrial&sprefix=F-F+j%2Cindustrial%2C191&sr=1-3
This project needs about 13 of these wires for a simple system. 3 more for additional hogline units. With the new case designs, only short wires are needed.
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You will also need three
6-32 x .75” machine screws..cost about $0.16 at the local hardware store.
AA Batteries for the laser beams; and could use in the sensor assemblies. NOT INCLUDED.
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