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[n_K]

So I'm experimenting with a SN54293 (datasheet: http://www.ti.com/litv/pdf/sdls097)
and I've came into a problem... I've got 2 chips, both salvaged from an old CCTV controller board.

I've tried using them with an astable 555 timer and a 74122 trigger system and it is REALLY sporatic when it works, rarely if I connect the power to it (4*AA batteries) it will work, most time it counts strangely, and doesn't use the 3rd or 4th bit (I'm driving LEDs) most the time too.

So I'm not really sure if I'm doing something wrong or what, not much point in posting a picture of the circuit (it's messy on breadboard) but basically pins 1, 2, 3, 6, 12 are unconnected, pins 4, 5, 8, 9 go to LEDs, pin 9 also goes to pin 11, pin 7, 13 go to ground and pin 14 goes to power and pin 10 goes to the 555 output or 74122 output.

Anyone got any idea why this is happening? I know TI shows the SN54293 as being obsolete but they've also got it in their current Z revision of logic devices

[n_K]

Bah, solved. Can't believe how lax they were when this chip was designed, no considerations taken into account for what the chip would be driving, need to use 4 transistors, one for each output, so it can drive the LED otherwise if adversely affects the chips function and completely messes it up, fair enough I should have RTFM a bit closer but that is just an awful design, and to only output 8mA per output... Can see why this chip is marked as obsolete!

Anyway if anyone else encounters the same problem I hope this advice helps you