* [http://www.gearbest.com/multimeters-fitting/pp_278738.html UNI-T UT136B] Multimeters ($16.56 each)
* [https://www.aliexpress.com/item/DHL-Free-Jinhan-JDS2023-Handheld-Oscilloscope-1-Channels-20MHz-oscilloscope-JDS2023-200MSa-s-16-bit-true/32804792194.html JDS2023] Handheld oscilloscope ($113 + battery)