Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

Vf vs If for Cree Sic Schottky Diode - Measured at cathode-relevant Currents

Posted by Maxamillion on July 5, 2009 at 11:29:41:

Since the Vf vs If plot supplied by Cree is really tailored to the higher end of the current range, I decide to measure it at currents relevant to use in cathode biasing. I set up a simple test rig using a AA battery (1.61V measured) and a series of resistors on the + leg of the circuit, to deliver a range of currents to the diode, then measured the voltage across the diode for each current.
The chart above shows the results for the current range of 2.79mA to 65.8mA for the 1A, 600V SiC Schottky Diode, Cree part # CSD01060A. Dynamic resistance looks to be ~1.6 ohms in the range of 10-65mA.
Although the Vf is a bit lower than that of an IR LED at 10mA (.84 vs 1.2V) the dynamic resistance (slope resistance) is more than 3 times less for the SiC Schottky diode, indicating it may be an excellent choice as a cathode bias diode (IR LED data from Morgan Jones' "Valve Amplifiers").
Now if we could just get some comparative noise data on the various diodes... I wonder whether the Schottkys would have an advantage here - they are known to be less noisy in switching applications, but the diodes do not switch on/off in a cathode bias application.