Abstract: A soldering system is disclosed having a stored program microcontroller by which one or more temperatures can be selected for a soldering iron tip. The system then automatically maintains such tip temperature during the soldering operation. The programmed microcontroller is coupled through input/output and interface circuits to a heating control that in turn is connected to the iron heater element for switching AC power in units of full waveform cycles across the element while the temperature of the tip is measured by a resistor sensor and an associated bridge measurement circuit so as to produce a signal that is applied to an input of the microcontroller forming a feedback loop. This causes the resistor sensor and hence the iron tip to reach the desired temperature.

Abstract: A temperature control circuit is disclosed utilizing automatically either the electric heating (or cooling) element or a separate sensor to measure the instantaneous temperature of the thermal load device. Either a pulsating dc or an ac electric power source may be used with the temperature sensing occurring at near-zero points of the source voltage waveform. The sensor forms one element of a Wheatstone bridge which when unbalanced by a value lower than a chosen reference value, causes a monostable oscillator to flip for at least several cycles of the source power. This turns on a power SCR to feed electric current to the thermal load to increase its temperature (and resistance) until the bridge is again balanced to reverse the state of the monostable oscillator and turn off the SCR. A simple, reliable two step, user friendly calibration circuit is provided for the temperature selecting component.

Abstract: Various electronic circuits are disclosed for controlling the temperature of an object by means of a resistive heating element. Some of the circuits include a digital display for displaying the actual temperature A plurality of different temperature sensors may be used, such, for example, as a resistive sensor, a thermocouple or a thermistor. The sensor may either have a positive or a negative temperature coefficient. Since most of the sensors are not strictly linear, different means are disclosed for compensating for their nonlinearity. Some of the control circuits feature a proportional control to which may be added an anticipatory control. Less sophisticated and more inexpensive circuits simply provide an on-off control.

Abstract: A pair of tweezers specifically designed for removing DIP (dual in-line pins) components or other electronic components from a circuit board. To this end, the tweezers include a pair of legs secured together at the top portion and having a sharply inwardly bent end portion formed with claws for engaging the pins of a DIP component. Near the curved ends of the tweezers there may be provided a bumper for each leg extending through an opening in the leg. The bumper serves the purpose to hold the DIP component between the curved end portions and the bumpers. A sliding clamp is provided which is of general U-shape and provided with an elongated slit. The clamp may be secured by a knurled nut extending through an opening in the legs of the tweezers. Hence, the clamp may be slid downwardly of the legs to squeeze them together. Thus, the opening between the jaws may be adjusted to the size of the component to be removed.

Abstract: A liquid dispenser includes a conventional syringe of the type having a piston, a piston rod, an actuating knob disposed in a cylinder, and a needle extending from the cylinder. The invention consists of a needle assembly therefor which includes a cap, a sleeve slidable on the needle and a retainer cap interconnecting the two. The cap is used for closing the needle to preserve the liquid and prevent spillage. The needle is provided with an inner coupler which may consist of two slightly spaced beads fixed to the needle near the end thereof. There is also provided an outer coupler into which may be fitted an extension tube by means of another inner coupler of the same construction as the first one. The inner coupler may be so mounted on the needle that its extension tube is housed in the inner needle, or it may be reversed so that the extension tube extends from the inner needle to extend the point at which the liquid is dispensed.