Connect it into your secondary circuit instead of the crystal detector.
The crystal detector achieves the same result in another way.
A crystal detector can be used with or without a battery while the vacuum tube detector requires two small batteries.
With a crystal detector receiving set you can receive either telegraphic dots and dashes or telephonic speech and music.
For this reason a crystal detector is sometimes called a rectifier, which it really is.
Don't expect to get as good results with a crystal detector as with a vacuum tube detector.
Don't be discouraged if you fail to hit the sensitive spot of a crystal detector the first time--or several times thereafter.
Don't use a wire larger than No. 80 for the wire electrode of a crystal detector.
Don't try to use a loud speaker with a crystal detector receiving set.
Don't expect a loop aerial to give worthwhile results with a crystal detector.