The relationships between the major circuit elements are shown in the block diagram opposite. The summing amplifier sums the voltages from the dial and from the sweep input, and its output controls the magnitude of the complementary current source and current sink. This current varies from approximately 5pA to 5mA for a 1000:1 frequency change (.002 - 2.0). The diode gate steers current into or out of the range multiplier capacitor and is controlled by the comparator output. When the comparator output is high the charge on the capacitor will rise, linearly, producing the positive going triangle slope. When the comparator output is low the charge on the capacitor will fall linearly producing the negative going triangle slope. The triangle amplifier has unity gain and buffers the triangle wave on the multiplier capacitor to drive the comparator and output circuits. The comparator operates as a window detector with fixed limit points set to the triangle peaks. One of its two outputs drives the TTL circuit and is also level shifted to drive the diode gate. The other output drives the squarewave shaper. When the comparator output to the diode gate is high the triangle wave is positive going until this reaches approximately +1V, the comparator output then switches low. When the comparator output is low the triangle wave is negative going until this reaches approximately — 1V, when the comparator output goes high, and the cycle is repeated. This basic function generator loop is shown by the double arrows in the block diagram. Triangle and squarewave are generated simultaneously as shown. To achieve the 10Hz range, the current steered by the diode gate is divided by 10 and the same capacitor is used as on the 100Hz range. The TTL circuit buffers one of the comparator outputs to drive the TTL output socket. The square shaper converts the comparator output to a current signal and applies it to the square wave function switch. The sinewave converter uses the non-linear characteristics of its diodes to convert the triangle wave into a sinusoidal current, which is applied to the sinewave function switch. The selected function is sent to the pre-amplifier, where it is inverted and buffered and applied to the output level control. The signal is summed with the voltage from the DC offset control at the output amplifier. This amplifier inverts and amplifies the signal up to 20V peak-peak to drive the 50Q output connector.