help with rs circuit

I have limited knowledge of electronics, trying to add some animations to a train set.
I need a rs flip flop circuit that will power a 5V relay, I've built two circuits, 1 using a 4011 chip and 1 using a 7476 chip both work to the volt meter pushing out 5v but when hooking up to a relay they either wont turn it on or wont hold it on, I don't understand why, and if there is an easier way I'm up for it, just need a circuit that when a button is pushed it will power a 5v or 12v relay until it receives a reset signal from a counting circuit.

Thankyou for any help that can be provided


Mike

The logic chips you mention can't provide enough current to drive a relay directly. Use a transistor to provide the current boost needed.

Look at the maximum output current that the chips can deliver and then look at the current the relay coil requires. You'll see the problem.

Use a ULN2003 and you won;t have to worry about the intracacies. https://www.ti.com/lit/ds/symlink/uln2003a.pdf The chip is capable of driving 7 relays, at 500 mA with an integral suppression diode. Note, the connections are strange. No power pin to the chip. The relays don't have to be 5V.

Your circuit could have power on reset issues, if that matters. Random state son power up.

KeepItSimpleStupid said:

Use a ULN2003 and you won;t have to worry about the intracacies. https://www.ti.com/lit/ds/symlink/uln2003a.pdf The chip is capable of driving 7 relays, at 500 mA with an integral suppression diode. Note, the connections are strange. No power pin to the chip. The relays don't have to be 5V.

Your circuit could have power on reset issues, if that matters. Random state son power up.

Click to expand...

Wow I just looked up, looks like it is the ticket to my problems ill try to figure out how to use it and let you know

Thank you very much

mike

Cool. Anytime you drive a really, you need a diode across the coil. This chip contains one. There is an 8 channel version too.

The chip is unique in another way too:

Connection OPEN - relay OFF
high in - Relay ON
Low in - Relay off