2 Transistor 4 state FlipFlop

Yesterday I did build the circuit (low power version). It actually worked the first time.

I did not use pushbuttons: instead of the S1 and S3 button, I simply touched the 15K - 2K2 connection with a wire to 5 volts, and instead of S2 and S4 I used a temporary wire to connect the low side of LED2 or LED4 to ground. So the 3K3 resistors connected to S2 and S4 were also not used.

The LEDs that I used did not respond well to the 0.5mA that th circuit provides. Raising supply voltage to 6 volt brought some more light (at 6 volt the circuit also worked well).

In the comments @matseng  said that he wants to build a memory system that also heats his room with 3000 Watt. Problem is, that the first design generates 1.1 Watt for 2 bits storage. So he can only store 5454 bits (680 bytes).

I made a new version for him, that uses only 50mW for two bits (10 mA at 5 volts). Now his 3000 Watt heating system will have 120kbit storage (15 kilobyte). That will be enough for some very nice programs ! 

The supply voltage was dropped from 12 volt to 5 volt, and low-current LEDs are used. All resistors were re-calculated. The file section has the Falstad model for this design.

(Note that in the Falstad simulator, you can edit the properties of a LED, and set the current that is needed to let them fully light up. So I did set that to 1 mA for this simulation.)