Page 4 of 8
dc_102019.pdf
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Install Q1, 2N3904 transistor
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Install J2, 3.5mm stereo jack
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Install J1, DC power jack
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Install C2,18,20, 100uF electrolytic capacitor,
observe polarity, the long lead is positive
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Install C15,16, 10uF electrolytic capacitor,
observe polarity, the long lead is positive
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Install J3, horz. pcb BNC female jack
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Use the T50-2 toroid core (red), wind T1 as shown below, use 36” of the magnet wire and start
winding at the 5 o’clock position. Push 1” of the wire down the hole from the top and hold it, feed
the remaining turns up from the bottom.
Every time the wire goes thru the center counts as one
turn
. Wind a total of 4 turns, and form a 1” loop and twist it as shown, and wind another 19 more
turns. If you have your own special technique for winding toroids, use it. The wires must be over
the core or under the core for each group of turns as shown below. If the wound core does not
look like the picture below, it will not align with the pcb holes.
Be sure to verify the turn counts
on each group before you trim the wires.
There should be a total of 23 turns with both windings.
A yellow core shown for clarity.
Note:
Now is a good time to mention a good way for counting the turns on your toroids. Many times on
a toroid with a lot of turns, you can lose track going around, as some are quite small. A good trick is to
take a digital picture of it
before
you trim the leads and enlarge it on your computer screen. Counting is
clearly a lot easier.
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Trim and straighten the wires. If you have wound it properly, when the leads are bent down,
they will align with the three pcb pads. The magnet wire has Thermaleze enamel, and can be
removed with a hot soldering iron. Remove the insulation, and tin the leads before installing on
the pcb. Now install T1 flat with the pcb, and solder the three leads.
Winding L1
L1 is specific to the band you want to build. See the band table below for the specific core and turn
count.
