Hacker News
new
|
past
|
comments
|
ask
|
show
|
jobs
|
submit
login
rcxdude
on April 21, 2014
|
parent
|
context
|
favorite
| on:
How to Convert a Digital Watch to a Negative Displ...
I think you can buy this kind of thing, I've seen them in use in some offices where sensitive information is being viewed.
Guidelines
|
FAQ
|
Lists
|
API
|
Security
|
Legal
|
Apply to YC
|
Contact
Search:
