Reddit reviews Franklin Sensors FS710PROProSensor 710+ Professional Stud Finder with Built-in Bubble Level & Ruler,Yellow

I have this and it works great to more visibly see the stud

https://www.amazon.com/Franklin-Sensors-FS710PROProSensor-Professional-Finder/dp/B0195K8OT4/

Get a better stud finder.

I have some experience with this.

1. Get a good stud finder. Most won’t work with lathe and plaster. This one does for my house. Your mileage may vary so buy from somewhere with an easy return policy:
   https://www.amazon.com/Franklin-Sensors-FS710PROProSensor-Professional-Finder/dp/B0195K8OT4/ref=sr_1_4?ie=UTF8&qid=1519272814&sr=8-4&keywords=ProSensor%2B710&th=1
   
   (Sometimes available at Costco)
   
   
2. Get a mounting bracket than will span between two studs.
   
   
3. Buy good lag screws (not too thick as your tv isn’t that heavy) vs. the typically crappy ones that come with the bracket. Something that looks like this (not necessarily these exactly):
   https://www.amazon.com/gp/product/B074ZMZMT9/ref=s9_acsd_top_hd_bw_b16qtJ_c_x_2_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-4&pf_rd_r=J14PERT8ZSKA9GRZVC1H&pf_rd_t=101&pf_rd_p=c0cdc314-6aee-50c9-b0bb-83f1e9593841&pf_rd_i=1640962
   
   
4. Mark where the bolts will go on the wall and predrill.
   
   
5. Mount the bracket using the screws but don’t overtighten as that will crack the plaster.
   
   Good luck.