2-3 second on/off timer for link tester

I've assembled this Ethernet Link Tester using a 23A (12v) battery and momentary switch and it works great. Now I'd like to add a timer circuit to it so that the transceiver is on 2-3 seconds then off 2-3 seconds. I mounted the battery, switch and female DB15 plug in a Radio Shack 270-283 project box so that I have room for the timer circuit.

The timer circuit will be connected to an on/off switch but I'd also like to use the momentary switch to bypass the circuit and power the transceiver directly.

I'm assuming I'll need a 555 chip and a relay (which would power the transceiver) but beyond that I don't have a clue how to proceed. I'd like to have both the timer circuit and the transceiver be powered by a single 23A battery, but I don't know what the duty life of the battery would be.

Any help with this would be greatly appreciated.

Mez

Any takers? I'm sure this is a very simple circuit but since I don't know the correct terminology to look for my Google searches haven't been helpful. I probably came across a working solution but just didn't recognize it as such.

Mez

It's a link tester? Where do you even find a AUI to 10bt adapter. Why not just power it from a wall wart instead of a 23A (Ah?) battery?
What are you trying to build?

blueroomelectronics said:

It's a link tester? Where do you even find a AUI to 10bt adapter. Why not just power it from a wall wart instead of a 23A (Ah?) battery?
What are you trying to build?

Click to expand...

The purpose of the momentary switch so that I can quickly determine whether a network jack is live. The purpose of the timer circuit is so that I can plug it into a network jack and then go to the switch and identify which port that jack is plugged into by the steady flash of the link light.

I know there are existing devices which do this and much more, but even the cheapest are $200 or more. I got the AUI adapters for $12 each (gotta love Ebay) and the components should cost maybe $20 total.

Mez

OK, in order to get different on/off times I need an astable 555 circuit, correct? If so, will this calculator work for me? Also, the relay will be connected between pin 3 and ground, correct? What will the output voltage be on pin 3 if Vcc is 12vdc? If it is high (over 9v) do I still need a relay or can I connect the transceiver directly to it?

Also, how do I choose the correct relay to use? I was planning on using Radio Shack # 275-241 (12VDC/1A SPDT Micro Relay). Will that work for this project?

Finally, is there a more energy efficient way to do this since I'm pulling from a fairly small battery (another post on here said 60mAH but I don't know for sure)?

Mez