AMBIENT LIGHT LEVEL DETECTOR INCLUDING TRANSIENT SUPPRESSION CIRCUITRY

• US 3,665,224 A
• Filed: 09/08/1970
• Issued: 05/23/1972
• Est. Priority Date: 09/08/1970
• Status: Expired due to Term

• Current Assignee: Newton D. Kelsey
• Original Assignee: Newton D. Kelsey
• Inventors: Kelsey, Newton D.
• Primary Examiner(s): Forrer, Donald D.
• Assistant Examiner(s): Dixon, Harold A.
• Application Number:
  US05/070,025
• Time in Patent Office: 623 Days
• Field of Search: 307/273,236,262,311,235 317/148.5 250/215
• US Class Current: 327/514
• CPC Class Codes: A01K 5/0291 with timing mechanisms, e.g. pet feeders
• CPC Class Codes: H03K 17/795 controlling bipolar transistors

Abstract

A circuit which includes a level detector circuit which is operated at two output levels, one level being indicative of a first ambient light condition and the second being indicative of another light condition, therebeing a timing circuit operated by the Schmitt trigger and an output circuit operated by the timing circuit after a predetermined delay to overcome transient and temporary changes in ambient light.

Claims

1. A circuit for detecting ambient light levels such as dawn and dusk for an animal feeder which comprises:

a light sensitive resistor means being incorporated in a voltage divider connected between two voltage levels, the midpoint thereof being connected with a level detector circuit forming an output signal at one of two levels, said level detector circuit having a predetermined threshold level;

said light sensitive resistor means being sensitive to variations of ambient light to cause said level detector circuit to form an output signal which is indicative of light levels above a certain predetermined level, and the other signal indicative of light levels below a certain predetermined level;

said level detector circuit being connected to a monostable multivibrator by means of a first coupling capacitor which is connected to the base of a transistor therein, and further including a second capacitor connected to the collector of said transistor within said monostable multivibrator;

an output circuit connected with the animal feeder for causing same to distribute animal feed; and

, said monostable multivibrator being connected between said level detector circuit and said output circuit means for operating said output circuit means for a time interval which is adjustable and which initiates only after passage of a predetermined interval of light level as sensed by said light sensitive resistor means.

2. A circuit for detecting ambient light levels such as dawn and dusk for an animal feeder which comprises:

a light sensitive resistor means;

a level detector circuit means incorporating said light sensitive resistor means therein and sensitive to changes in resistance thereof as a result of variations of ambient light, said level detector circuit means forming two output signals across an output resistor, one indicative of light levels above a certain predetermined level and the other indicative of light levels below a certain predetermined level;

a pair of capacitor means connected with said output resistor;

a first transistor switch means connected to one of said capacitor means at its base;

said transistor means including a collector which is connected to the second capacitor means, said means further including a load resistor through which current is developed by said transistor means when it is switched on and off;

additional circuit means connected to said transistor means for controlling the interval of time the voltage level at the collector of transistor means is maintained at a level initiated by a signal from said level detector circuit means initiated by a signal from said level detector circuit means coupled through one of said capacitor means;

an output circuit connected with the animal feeder for causing same to distribute animal feed; and

, said transistor means being connected to said output circuit means for operating said output circuit means for a time interval which is adjustable and which initiates only after passage of a predetermined interval of light level as sensed by said light sensitive resistor means.