Patent GB-1171006-A (GB)
Title: Magnetic Tape Recorder.
IPC: G11B5/86
Filed: 1967-05-26
Abstract: 1,171,006. Cartridge and open reel magnetic tape recorders. AKAI ELECTRIC CO. Ltd. 26 May, 1967 [25 July, 1966], No. 24723/67. Heading G5R. A tape recorder includes a capstan for moving one tape past a first group of magnetic heads from one open reel to another, a second capstan mechanically coupled to, for synchronous drive with, the first capstan, for moving a further tape past a second group of magnetic heads, and an opening in the casing through which a cartridge containing the further tape can be inserted and withdrawn for co-operation of the further tape with its capstan and heads; a pre-amplifier system followed by a recording amplifier are also provided. Preliminary manipulation.-Main switch 239 is closed, whereupon motor 304 drives flywheel 228, through belt 232, to rotate capstan 214 for the open reel tape To and capstan 229 for the cartridge tape Tc. Open reel recording.-Knob 204 is turned clockwise, whereby pressure roller 213 is pivoted towards capstan 214 to feed tape To from supply reel 218 to take-up reel 219, and button 209 is depressed. Audio signals are applied to input 8 and pass through two stages of amplification, with negative feedback of both stages. The preamplified current is passed through a leveladjusting resistor to a recording amplifier, which has a trap circuit in its output to block current from a biasing oscillator. Knob 206, for pre-selecting one of three speeds, also operates rotary switches governing various inductorcapacitor combinations to match the recording amplifier to the chosen speed. The recording amplifier output is fed partly to record/playback head H1 and partly to a volume unit indicator 9. During recording, biasing current is fed to a head H3, which has been pivoted towards the tape by turning of knob 204, and erasing current is fed to a head H2. Open-reel playback.-Knob 204 is turned counterclockwise and button 209 depressed. The audio signal picked up from tape To by head H1 is preamplified in two stages, with negative feedback to the first stage, only, through a C-R combination different from that used during recording. The signal from the second stage passes in part through the recording amplifier, but thence to earth, and in part to a tone-quality network in front of the input of a main amplifier. Here the signal is fed in parallel through a high resistor in one branch and a capacitor in series with a potentiometer and slider in the other branch to the main amplifier, the other end of the potentiometer resistance being earthed. The output from the main amplifier is shared between a loud-speaker and the indicator 9. Cartridge recording.-Knob 204 is turned clockwise and button 210 is depressed. Speed knob 206 need not be manipulated because there is only one speed for the cartridge tape Tc. Audio signals applied to input 8 are passed through two preamplifier stages and the recording amplifier as before. In this case bias current is added to the recording current for feeding to the head H4 which is a combined recording/ playback/bias head. Erasing current is fed to an erasing head (H5), (Fig. 3, not shown). Cartridge playback.-Knob 204 is turned counterclockwise, and button 210 again depressed. The audio signal picked up from head H4 is passed through the preamplifiers, tonequality network and main amplifier, approximately as before, and fed to the loud-speaker. Dubbing.-An audio signal recorded on the open reel tape To may be re-recorded on the cartridge tape TC.