Ramsey UT5 Bedienungsanleitung PDF herunterladen (Seite 7)

UT5 - 7

 12. Now, choose monostable (timer) mode or astable (oscillator) for your first project or test. Simply install a jumper

wire and/or R6 (1K: brown-black-red) as follows:

MONOSTABLE MODE: (install Jumper 1 only).

ASTABLE MODE: (R6 as J1 and J2 both installed).

 13. After studying the application ideas in this booklet, install your choice for C1. If you use an electrolytic

capacitor,observe correct polarity. If you use a disc capacitor such as a .1 uf for high oscillator frequencies, there is

no concern about polarity.

UT5 AND 555 IC THEORY OF OPERATION:

In the Monostable Mode, a negative input at terminal D causes pin 2 of the 555 to pull low momentarily. A positive

input pulse at terminal C causes transistor Q1 to turn on, pulling pin 2 of the 555 towards ground. Capacitor C1 is

normally held discharged by a transistor within the IC; when pin 2 is pulled low, a flip-flop inside the 555 is set. This

releases the short across C1 and also sets the output (pin 3) high. C1 will now begin charging through R3 and R4.

When the voltage across C1 reaches 2/3 of the supply voltage, the comparator resets the flip-flop, causing the pin 3

output to go low and also turning on the transistor which shorts C1.

In the Astable (oscillator) Mode, the trigger (pin 2) and the threshold (pin 6) are tied together, and the internal

discharge transistor (pin 7) is tied to the trigger through the timing resistor. In this mode the circuit will repeatedly

trigger itself as C1 discharges through R6 and charges through R6,R4 and R3.

Timing is completely independent of the supply voltage used.

1 2 3 4 5 6 7 8 9 10 11 12 ... 17 18

Keine Kommentare

Ramsey UT5 Bedienungsanleitung Seite 7