What Capacitor Values for Crystal Oscillator Circuit? - Page 1
Forum section: electronics / rf-microwave

author: Fionaa
author_rank: Contributor
timestamp: March 09, 2025, 04:13:07 pm
content: This Circuit was Originaly For an 8 MHz Crystal, i googled and i saw many different Values for C1 and C2 like C1 220pF C2 220pF or C1 330 pF C2 18 pF, what value should i pick for safe drive levels of the Crystal and Stability?the datasheet of the Crystal is:https://wmsc.lcsc.com/wmsc/upload/file/pdf/v2/lcsc/2310241351_KYX-KUS050002030_C19076825.pdf

author: A.Z.
author_rank: Super Contributor
timestamp: March 09, 2025, 06:56:29 pm
content: duplicate discussionhttps://www.eevblog.com/forum/rf-microwave/will-this-circuit-fry-my-crystals/msg5823213/#new

author: Fionaa
author_rank: Contributor
timestamp: March 10, 2025, 07:38:59 am
content: Well its an BJT Oscillator Now

author: A.Z.
author_rank: Super Contributor
timestamp: March 10, 2025, 08:02:31 am
content: Quote from: Fionaa on March 10, 2025, 07:38:59 amtoo complexhttps://www.tompolk.com/inventions/455_KHz_Oscillator/455_KHz_Oscillator.html

author: Fionaa
author_rank: Contributor
timestamp: March 10, 2025, 04:30:09 pm
content: Thank you so much, Thats Simple enough :3

author: LM21
author_rank: Regular Contributor
timestamp: March 11, 2025, 10:12:02 am
content: That circuit will probably work. Why don't you try. It is the easiest/best oscillators I know.If you google Colpitts oscillator, you'll find plenty of info.But you should really build it, then you will know.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: March 11, 2025, 10:34:06 am
content: Back in 1975 Dr Ulrich Rohde DJ2LR (of Rohde and Schwarz), designed a crystal oscillator with low phase noise as the crystal filters the output. Kind of neat idea. The BFO circuit in my home made receiver uses the same design idea, check the CW oscillator in the lower left of the circuit. Obviously for most purposes you don't need the diode and associated Rs and Cs in the output.https://www.qsl.net/g4aon/pdfs/BFO%20v2_3.pdfSJ

author: RoGeorge
author_rank: Super Contributor
timestamp: March 12, 2025, 12:32:58 pm
content: Quote from: A.Z. on March 10, 2025, 08:02:31 amMy guess is, that might work even without the resistor, if instead of connecting the BJT and the filter in parallel, the reversed BE and the resonator are put in series with the battery (but I didn't try).

author: A.Z.
author_rank: Super Contributor
timestamp: March 12, 2025, 05:50:47 pm
content: https://en.m.wikipedia.org/wiki/Negative_resistancehttp://agostalab.clarku.edu/TheTDO.htmlhttps://www.tutorialspoint.com/sinusoidal_oscillators/sinusoidal_tunnel_diode_oscillator.htmdeep SIGH

author: Fionaa
author_rank: Contributor
timestamp: March 23, 2025, 05:08:06 pm
content: It Works but how can i make an Small Beacon Transmitter out of it

author: A.Z.
author_rank: Super Contributor
timestamp: March 24, 2025, 04:51:45 pm
content: Quote from: Fionaa on March 23, 2025, 05:08:06 pmPlease, pleaseread the subject of this discussion.

author: antenna
author_rank: Frequent Contributor
timestamp: March 25, 2025, 04:28:32 am
content: Quote from: Fionaa on March 23, 2025, 05:08:06 pmhttps://www.talkingelectronics.com/projects/Beeper%20Bug/BeeperBug.html