GB1505272A - Voltage regulation apparatus - Google Patents

Abstract

1505272 Volume control S H LAMPEN 11 April 1975 15024/75 Heading H3Q [Also in Division H1] A voltage adjusting arrangement, e.g. for use as a volume control in an audio amplifier, comprises a device 10, Fig. 1, having resistive and conductive tracks 11, 12 in a spaced, elongated configuration and with a voltage gradient V 1 -V 2 along the resistive track 11 whereby the user can, with a finger, establish contact between the two tracks at a selected point along their length, e.g. point 14, a corresponding output voltage of the device being fed to a storage element such as capacitor C1 via a switch S 1 which is closed only while the contact is established. The storage element holds the selected voltage which is used, e.g. to control an audio signal level by means of a voltage controlled amlifier A4, Fig. 4. This Fig. also shows the use of LEDs 48a-48n which are spaced along an elongated control device 40 and a number of which are lighted depending on the set signal level. The capacitor Cl is charged via a diode Dl, and a leakage resistor R2 is provided to reduce the charge on C1 when the device output is selected at a level below the previous setting. The switch S 1 may be a relay which is closed by a voltage comparator Al as soon as any output voltage appears on the conductive track 12 or 42, the resistive track 41 being flexible in the Fig. 4 arrangement. Alternatively the switch may be a transistor as illustrated in Fig. 5 (not shown), with buffer circuitry for maintaining the voltage on the capacitor C1. The output voltage of the device may be stored digitally in an 8-bit up-down counter (80, Fig. 6, not shown) instead of in a capacitor, the counter outputs being fed to a digital-to-analogue converter (90). The device may use a bridging contact arrangement (Fig. 3, not shown), or the operator's finger may itself bridge the two tracks. The "conductive" track may be of high resistance.