https://wiki.rev0.net/index.php?action=history&feed=atom&title=Rev0VTx_Modulator 2026-06-04T04:18:23Z Revision history for this page on the wiki MediaWiki 1.39.1 https://wiki.rev0.net/index.php?title=Rev0VTx_Modulator&diff=333&oldid=prev 2015-08-08T02:03:01Z

<p>Created page with &quot;This page describes the 5.5 MHz Audio Subcarrier AM Modulator for the rev0VTx video transmitter. ==Summary== File:Rev0VTx_MOD_Sch.png|thumb|right|Schematic for the rev0VTx...&quot;</p> <p><b>New page</b></p><div>This page describes the 5.5 MHz Audio Subcarrier AM Modulator for the rev0VTx video transmitter. <br /> <br /> ==Summary==<br /> [[File:Rev0VTx_MOD_Sch.png|thumb|right|Schematic for the rev0VTx Mod.]]<br /> [[File:Rev0VTx_MOD_Brd.png|thumb|right|Board for the rev0VTx Mod.]]<br /> <br /> The modulator is based on the topology used in the [[900MHz_Video_System|HobbyKing 900 MHz Video System]]. The design uses two BC817 (or similar) NPN BJTs, with a series resonant circuit made of a 10uH SMT inductor and variable/fixed capacitor. The first transistor forms the oscillator, and is amplitude modulated by applying the ~1-2Vp-p audio signal to the collector. A second transistor amplifies the modulated carrier. The board runs from a single 5V supply. The design was simulated and evolved in LTSpiceIV, using the built-in BC817 model. The Spice circuit for simulation can be found here: http://www.rev0proto.com/files/rev0VTx_MOD_Sim.asc The gerbers, Eagle schematic and board file can be found here: http://www.rev0proto.com/files/rev0VTx_MOD.zip<br /> <br /> [[File:Rev0VTx_MOD_Sim.png|thumb|640px|none|5kHz Audio modulated 5.5MHz carrier as simulated in LTSpiceIV.]]<br /> <br /> ==Testing==<br /> <br /> ==PCB/Construction Photos==<br /> &lt;gallery perrow=3 widths=240px heights=120px&gt;<br /> File:rev0VTx_MOD_PCB_Bottom.jpg|Bottom of unpopulated PCB<br /> File:rev0VTx_MOD_PCB_Top.jpg|Top of unpopulated PCB<br /> File:rev0VTx_MOD_Top.jpg|Populated PCB<br /> &lt;/gallery&gt;</div>

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