Collecting scheme to delay the inclusion of a CRT according to the article A. Ilyin (RL 4-95), option to block MC, I found that this device needs some improvements.
1. The Zener diode VD1 is used in the scheme as a key element operable voltage, and operating current here is much less than 3 mA - the minimum on those. conditions. In this mode, the Zener diode 156 COP the threshold of the opening was only about 2 In (at a current of 30 μa). Therefore, to increase the delay time and more efficient use of the capacity C1 is better to install in series with the VD1 of the second Zener diode VD1.1. To increase their operating current, it is desirable to reduce R3 to 30 ohms.
2. When the capacitance C1 220 µf, the device is ready to re-enable no sooner than 30, because the discharge occurs through R4 with a higher resistance. To accelerate this process R4 should shall be shorted diode VD2. When charging it is closed the voltage source +12V, and after turning off the TV - offer potential with C1, and discharge quickly through the forward resistance of the diode.
3. Instead of C1 6.3 better to take In the condenser 25 V. the Capacitors to higher voltage more stable, and most importantly, less "dry out" over time.
The same considerations apply to option to block MS, because they have the same node of the formation of the delay interval.
Author: A. Skorupki, Saratov, Russia; Publication: N. Bolshakov, rf.atnn.ru