[LectronFanModerator]

Hi all,

Let’s build a circuit of  the Lectron 1007 Digital Lab !

In the early days, logic circuits were build using switches and relays.

Very good examples were the electro mechanical pinball machines where switches, relays and motors were used to make decisions, counting, switching states, etc.

Experiment 23 of the Digital 1007 set is a nice rendering of how simple decisions can be made with switches and a relay.

Note also the 120 Ohm resistor to protect the relay coil. This resistor should always be implemented when using the relay to extend its life.

A question for our Lectroneers : who can make a truth table with all different switch settings and lamp output ?

Good luck !

• This topic was modified 5 years, 1 month ago by Michael.

[MichaelKeymaster]

Hi Frank,

I am not the most logical person ….

Thank you for this challenge!

M.

[GuentherParticipant]

Hi all,

I am not the digital expert, so I had to look at my “TTL Introduction Manual” (idea: Max Guerth, ~ 1971).

The “normal” [E]XOR truth table looks like this:

The above circuit with the relay and three (!) switches is rather confusing to me, because there are 3 x 2 states. That are – from my point of view – this combinations, where the A and B inputs are not really clear to me – sorry…

The switches are numbered from left to right. Maybe you have an explanation which I may understand 😉

Best,

G.

• This reply was modified 5 years, 1 month ago by Michael. Reason: Changed font and size styling for easier reading

[LectronFanModerator]

Well folks, what we have here is a circuit that can be found in our house.
We have a large corridor with only 1 light bulb and 3 switches located at different spots.
It is obvious that each switch can turn the lamp either on or either off.
This can be simulated with our Lectron set
Our Lectron circuit is a little bit different in the fact that we have only SPDT (Single Pole Double Throw) switches.
To make the situation work we are using the relay who’s has DPDT switches.
Your truth table is correct, but let’s assume this :
Switch Nr1 UP = 1 and down = 0
Switch Nr2 LEFT = 0 and RIGHT = 1
Switch Nr3 UP = 0 and DOWN = 1
We would have a truth table like this :
So in short, the light bulb will only lit when an uneven count of switch positions will be on.
In your table, A and B are the 2 inputs of an EX OR gate.
In our example, we would have A, B and C since we have a 3 input EX OR gate.

Greetings

• This reply was modified 5 years, 1 month ago by Michael. Reason: Changed font and size styling for easier reading
• This reply was modified 5 years, 1 month ago by LectronFan.
• This reply was modified 5 years, 1 month ago by LectronFan. Reason: Table not correct

[MichaelKeymaster]

Sorry Frank,

Not sure why your table html is not being parsed correctly.

Best,
M

• This reply was modified 5 years, 1 month ago by Michael.

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