Engineer Sergii Zadorozhnyi website
Simple SolutionsEngineers and radio amateurs are interested in the static parameters of JFETs (Junction gate Field Effect Transistor), such as the zero-gate voltage drain current (IDSS) and the gate-to-source cutoff voltage (VGS(off)), as a rule, either when choosing JFET with the best parameters, or when selecting a pair of JFETs with the equal parameters for the differential stage. In this article, we will focus on the use of static parameters in the calculation of circuits based on JFETs.
Read MoreRefinement of the DEGEN DE1103 Radio Receiver: Applying the Signal from the Antenna Directly to the Input of the First Mixer
Wednesday , 4, July 2012 Radio, Solutions Leave a comment
The modification of the DEGEN DE1103 radio receiver described below was done to provide the radio receiving in long and medium wave bands with an external antenna (or with the standard telescopic antenna), but not with the built-in ferrite rod antenna. Now while working on short waves too, the received signal from the standard telescopic or an external antenna is applied directly to the input of the first mixer, bypassing the Q1 transistor stage.
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Using special soldering iron tips or a hot air gun to desolder surface mount chips in a TQFP package carries the risk of overheating the chip and / or printed circuit board. Below is a method for safely removing chips in a TQFP package – without overheating and with the ability to reinstall the desoldered chip. It does not require any special soldering equipment.
Read MoreMarch 1, 1941 can be considered the day of the appearance of FM radio broadcasting in its usual form, that is, as a commercial industry, when the W47NV radio station with a transmitting center in Nashville, Tennessee, USA, went on the air for the first time. Here is how the American weekly “Broadcasting” wrote about this on March 10, 1941 in the article “New FM Station of WSM, in Nashville, Starts Operation With 70 Hours Weekly”:
Attachment to Voltmeter for Measuring Static Parameters of JFETs
Monday , 4, July 2011 Measuring Leave a comment
To find out the parameters of JFETs, both n-channel and p-channel, the simple and inexpensive attachment to the voltmeter described below will help, which allows you to measure a zero-gate voltage drain current (IDSS) and a gate-to-source cutoff voltage (VGS(OFF)). Thus, using only this attachment with some kind of voltmeter, you can, for example, select JFETs with the best characteristics or select a pair of JFETs with the same parameters. In addition, the attachment allows you to check JFET for performance, to clear up the transconductance at the intended DC operating point, and for students and novice radio amateurs to examine the field effect transistor in order to better understand its principle of operation.
Read MoreAudio of Testing Anti-noise Ferrite Rod Antenna “Olusha”
Saturday , 12, March 2011 Radio Leave a commentAn experiment with an audio recording of the reception of a broadcasting radio station in the medium wave band was carried out in order to once again confirm the ability of the anti-noise ferrite rod antenna “Olusha-10” to suppress industrial and domestic radio interference. The principle of operation of the “Olusha-10” antenna is described in detail in the author’s article “Suppression of Common-mode Interference to Radio Reception”.
Read MoreMatched Load: Theoretical Foundations of Practical Benefits
Sunday , 4, July 2010 Radio Leave a commentIn the educational literature, load matching is most often considered in relation to the wave properties of a long line during the transmission of a high-frequency signal. But here the energy relations are considered during the transfer of energy from an active two-terminal network to a passive one.
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