Hobbies And Interests
709
Developed in 1965, the 709 op was not the first of its kind, but it became one of the most popular. As with earlier designs, it has inverting and non-inverting inputs and a single output. In addition, it has terminals for external capacitors to stabilize the circuit for high frequency applications. Though it originally sold for $70, demand and mass production allowed its price to drop to $10, then $5.
741
The 741 is an improved op that used the 709 as a starting point. Designed to capitalize on the 709's popularity, the arrangement of the 741's main input and output pins is the same as that of the older device. It has internal frequency compensation, so it needs no external capacitors. This makes it a simpler device to use than the 709. It requires a bipolar power supply, meaning it needs positive, negative and ground for its direct current (DC) power.
358
The 358 has two separate, independent op-amps in a single 8-pin IC package. The dual op design further streamlines circuits, as many call for multiple op amps. It functions much as a 741 does, though in a more compact package. The 358 can run from either a single voltage supply and ground or a bipolar power supply.
13700
An operational transconductance amplifier, or OTA, converts voltages into currents, so its output is a current instead of a voltage. Engineers use these devices, such as the 13700, together with standard op amps to design certain types of electronic equipment, such as variable-frequency oscillators or variable low-pass filters. The 13700 has two OTAs on a 16-pin IC. The package also includes two current-to-voltage buffer amplifiers as a convenience for designers.