The 74123 TTL integrated circuit consists of a monostable that can be configured to generate voltage-controlled signals, as shown in the figure. The maximum frequency of this circuit can reach a few tens of megahertz and even more if the faster subfamilies of the 74123 are used. In this circuit, the control voltage varies between 0 and 6 V (it can be a little more than the 5 V of the supply) when frequencies are obtained according to the graph of the same figure. In this case, the frequency will typically vary between 10 and 60 kHz, with rectangular signals at the output. The amplitude of the signals is equal to the voltage used in the supply, in the case of 5 V. The diodes used in this circuit are of general use such as 1N4148 or equivalent.
