Skip to main content

A Note About PC Board Layouts

Gyrator I & II - Parts Layout Mistake Resolution

The articles in section 2 and 3 of the SID Equipment list both show PC Board layouts that contain an error concerning the polarity of the power supply diodes and in the case of section 3, the output rectifier diodes. The following descriptions summarize the changes that should be made.

Section 2
A Gyrator Tuned VLF Receiver
Reference Gyrator I

The parts layout depicts D3, C7, C9 wired to pin 7(v-) of the 4136 amplifier and D4, C8, C10 wired to pin 11(v+). This is incorrect. When assembling the board these components, along with the indicated polarity, should be swapped one to one for proper orientation

Section 3
Gyrator II An Improved Gyrator Tuned VLF Receiver
Reference Gyrator II

The parts layout depicts the anode(+) of D4 going to pin 8(v+) of the two TL082 op-amps and the cathode(-) of D5 going to pin 4(v-) of the same chip. This is incorrect. When assembling the board mount the two diodes with the reverse polarity as indicated on the parts layout diagram.

In addition mount diodes D1,D2, D3 as follows:

D1 Anode to ground
D2 Cathode to recorder output
D3 Cathode to recorder output

Capacitor Polarity
In both cases the polarized capacitors should be installed such that the polarity of the capacitor matches the voltage polarity to which they are being connected.

In other words . . .

The positive supply has the capacitor connected with (+) to (V+) and (-) to ground.
The negative supply has the capacitor connected with (-) to (V-) and (+) to ground.
Keywords:
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484