Gated Pulse Frequency Generator Schematic

[Login to see usernames]

Here's the schematic for the gating signal.
There is some bleed through from the back of the sheet,but it's still readable.Someone can do a better job with MS Paint or whatever (TONY)
Don
 

[Login to see usernames]

Thank you Don for this piece of the puzzle.  I know I won't be the only one building and experimenting with this. 


Regards,


kb

[Login to see usernames]

here's a nice summary page of the circuits surrounding don's quiz question circuit


http://www.rexresearch.com/meyerhy/wo92.htm


kb

[Login to see usernames]

Don, A26 you didn't label it...is it a 74122???

(http://www.globalkast.com/images/tonywoodside/Fig.6-values.png)

[Login to see usernames]

Don, A26 you didn't label it...is it a 74122???

(http://www.globalkast.com/images/tonywoodside/Fig.6-values.png)

74123 will work better because the inputs are combined within the chip instead of tying them together outside like pins 1&2 and 3&4

[Login to see usernames]

Tony, yes it's a 74122. Q10 and Q11 were small black transisters. 2N2222 are metals ones.
Don

[Login to see usernames]

Thanks Don....you can also get the 2N2222 in the black plastic packages, they are listed as 2N2222A. Also I noticed that you have the resistor coming from the base of the transistor marked as a 47k, is this correct? I would think it would be a 4.7k instead. Are all the caps you have listed here ceramic and tantalum types?

[Login to see usernames]

Yes the resistor at the base is a 4.7k,I marked it wrong.The cap across  pins 11 and 13 of the 74122 is an electrolytic,non-polarized.The rest are like you think.
Don