Electric circuits for use in camera

An electric circuit for use with a camera comprising a shutter, said circuit comprising:

• an electromagnet for controlling said shutter;
• an integrating circuit comprising light responsive means, a condenser, and a resistor;
• trigger switch means connected to said condenser to short-circuit the condenser under selective conditions and to allow a voltage to build up in said condenser during exposures;
• actuating means connected to said integrating circuit to be controlled thereby, said actuating means being connected to said electromagnet to actuate said electromagnet when voltage across said condenser reaches a predetermined value;
• a switching element operated by a signal from a current flowing through said resistor;
• alarm means connected to said switching element to be controlled thereby;
• terminals for synchronizing a flash source;
• a thyristor comprising an output circuit connected in series with said terminals;
• an X contact connected to said power supply means and connected to an input terminal of said thyristor;
• said switching element comprising a second thyristor connected to said X contact and having an input terminal;
• and
• circuit means connecting said light responsive means to said input terminal of said second thyristor to cause said second thyristor to be conductive when there is sufficient light to make it unnecessary to use a flash source, said second thyristor connecting said X contact to a source of potential to prevent said first thyristor from becoming conductive when said second thyristor is conductive.