A mini relay like chip?

Community General Discussions
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1

Here is the setup, I need a picaxe to "push" 2 buttons when it receives a high digital input.
I will be using a picaxe08M and will have 2 digital inputs(2 buttons) and to digital outputs to triger the relay.
I need somethink like a relay but much smaller, about the same size a the picaxe chip.
It only need to handle 5V.
Anybody know of something that would do the job ?
2

How much current/voltage are you switching?

There are reed and opto relays in a Dual Inline Package (DIP) form factor like an IC. Be sure to check the specs for the appropriate voltage and current limits of the relay.

Opto relay examples:

http://parts.digikey.com/1/parts-kws/panasonic-electric-works-solid-state

Reed relay examples:

http://parts.digikey.com/1/parts-kws/dip-reed-relay

Do you definitely need a relay? What sort of current/voltage connection are you making? Can you explain your need for the size limitation? DIP package relays are not that big.

3

how about an LM386?
It wouldn’t really work exactly like a relay, but it would be able to crank higher voltages with just a digital out …

4

I only need to be able to

I only need to be able to control 2 buttons so only need 2 digital outputs. <o:p></o:p>

The circuit I am making is to push the start and reset button on a C-Stamp (more complicated version of a Picaxe), the C-stamp runs on 5V and for a button to be “pushed” it need to be connected to G trough a resistor. <o:p></o:p>

5

Not a relay exactly but
Not a relay exactly but something that works in the same way, a small current that can operate a switch that controls a much larger current, in this case the Picaxe will be receiving 5V and the C-stamp works on 5 V so the voltage difference is not the problem I just need a switch that can be controlled by a high or low input…

6

It seems to me like he want

It seems to me like he want a curcuit that is normally closed, but when 5v is applied to the controll input a connection is established between to other connectors. So he wants the funtionality of a relay, but in a smaller package…

 

I suggest you read up on the links posted by ignoblegnome and deside what kind of voltages you plan to use.

7

Just use the digital outs through a resistor

The Picaxe digital outputs can sink or source about 20 mA each. Couldn’t you just run the outputs through a 330 ohm resistor and set them to logic low to trigger the start and reset buttons on the C-Stamp? Since you are just driving 5V logic, there should be no need for additional current drivers like a Darlington or external transistor.

Am I missing something?

8

I don’t get the big
I don’t get the big deal…If 20 mA are enough then just to as ignoblenome suggested, if you want some more then a BJT transistor does the job, that’s all!

9

Does a switching transistor
Does a switching transistor act as a relay?

10

They both can be considered

They both can be considered switches, the only difference is the way you switch them on and some other things. For example, a transistor is much faster than a relay, but the relay is better if used for high voltage applications.

In vince’s case, they both would do the job, so going for transistors makes it cheaper.

11

Relay driver
A ULN 2003 is perfect for relays and is rated at 500MA. It has 7 drivers and cheap too. I would send the data sheet but don’t know how. Google it.

12

It just sounds too simple if

It just sounds too simple if you know what i meen, but I will still try.

Just finished puting the circuit together, wil lhave to wite a simple code and test it.

13

Thanks for all the help


Thanks for all the help !
It turns out that connecting the switch to my Picaxe through a 330 resistor and setting the pin to LOW was all that I needed to trigger it !
I will try to integrate this idea in to my current robot so that reseting and starting the micro controller will be that little bit simpler.