Ramsey Electronics FM100B, Инструкция по эксплуатации

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FM100B
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E. BARGRAPH PEAK HOLD
In this section we will be installing the parts that monitor the peak audio levels
and holds them for a long enough period so that we can see the value on the
meters (this section is located toward the back of the board). We will also be
installing a few capacitors that are actually part of the mixer section (for
convenience we decided to install them here).
1E. Install R91, a 47K ohm resistor (yellow-violet-orange).
2E. Install R71, another 47K ohm resistor (yellow-violet-orange).
3E. Install D6, a 1N4148 type diode (orange glass body with black stripe
on one end). Make sure this diode is installed in the correct way with the
stripe on the same end as shown in the Parts Layout Diagram. This diode
and its surrounding circuitry rectifies the audio signal into a DC level.
Capacitor C81 then holds this level for a long duration. The resistance of
R91 then determines how long C81 holds its charge (the less the value the
less time C81 holds the charge). This is seen on the bargraph meters
when you have a single pulse like a drum beat.
4E. Install D5, another 1N4148 type diode (orange glass body with black
stripe on one end). Again check orientation before soldering. This is the
rectifier for the other channel.
5E. Install U7, a LM358 opamp. Make sure to orient it in the same direction
as shown in the Parts Layout Diagram. Check all 8 pins to be sure they are
through the board before soldering any of them!
6E. Install C81, a 10 uF electrolytic capacitor. Check polarity!