Byers, J.A. 1983d. Electronic fraction collector used for
insect sampling in the photoperiod-induced diel emergence
of bark beetles. Physiological Entomology. 8:133-138.
An electronic timer and fraction collector consisting of CMOS
integrated circuits is described. It converts 50- or 60-Hz AC to
real-time pulses in programmable whole-number increments (1, 10 or 60 s)
from 3 to 16659, producing timing periods from 3 s to more than 11 days.
The fraction collector contains a leaf-switch feedback circuit that
automatically adjusts to various gear motor speeds and sample tube
spacings so that proper positioning results. Hourly collections by
the device of the bark beetles Ips typographus L. and Pityogenes chalcographus L. (Coleoptera: Scolytidae)
emerging from logs of Norway spruce,
Picea abies, indicated that both species emerged with a diel
periodicity. A unimodal emergence peak for both sexes of both species
occurred at midday in LD (L = light, D = dark) 20:4 at a constant
25 degrees C and 80% r.h. (relative humidity).
FIG. 1. Schematic circuit of the timer section of the fraction collector (60-Hz AC). The cycle time is
set by (1) the 3-position rotary switch at 1, 10 or 60 s and by (2) programming IC
5 by means of DIP switches at the left of the figure as indicated. For example, a cycle
time of 631 s is obtained by setting the rotary switch at the 1s place and closing the first
DIP switch in the "Units" section plus the first and second switches in the "10s" section (1+2)
and the second and third switches in the "100s" section (2+4) to yield 1+30+600 = 631 s. All
switches are each connected to ground through a 30 K Ohm resistor as indicated for the last
two switches in the "1000s" section. Timing is initiated by first connecting the Start switch to ground for at
least 3 clock pulses and then opening the switch at the desired starting time.
ICs 1, 2, and 4 have +12 V (DC) applied to pin 14 and ground to pin 7, while IC 3 has +12 at pin 16 and ground
at pin 8. *Pins 8, 9, 12, and 13 of IC 12 are connected to ground. All resistors are 0.25 W.
CMOS integrated circuits should not be inserted into their sockets until all connections have
FIG. 2. Schematic circuit of the 50-Hz AC divider section to be inserted in Fig. 1 (for use in Europe) instead
of the corresponding American (60-Hz) circuit consisting of IC 3, IC 1B, and IC 4A and B. The same power
connections are used as in Fig. 1; in addition IC 8 requires +12 V at pin 14 and ground at pin 7.
FIG. 3. Schematic circuit of the test-tube position sensor and motor turn-on interval control section of the
fraction collector that will accomodate various gear motors of <2 rpm. *Pins 7, 12 and 13 of IC 7 and pin 8 of IC 6 are connected
to ground while pin 16 of IC 6 and pin 14 of IC 7 are connected to +12 V (DC).
FIG. 4. Diagram of fraction collector in cross-sectional side view. Two discs (A and B) are drilled appropriately around
the circumference to hold test-tubes, separated by two support blocks (C), and held in place by two rings with set
screws (D) above and below. The test-tube-holding discs are rotated by an axle (E) in bearing (F) attached to a stand, and the axle
is fitted with the shaft of the gear motor (G). An adjustable block (H) is attached to the normally open leaf-switch (I) which detects
the position of test tubes (J), and wires from the gear motor and leaf-switch (K) connect to the control unit (see Fig. 3).