John's Question About 11mA 8-Pin Relay

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Discussion Overview

The discussion revolves around the use of an 11 mA 8-pin relay, specifically focusing on its pin configuration and how to effectively switch a load on and off using various relay types, including latching and reed relays. Participants explore circuit designs and configurations suitable for controlling the relay with specific input signals.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • John inquires about the pin configuration for the relay and how to use it to switch a load.
  • One participant suggests that the two isolated pins are for the input coil, and the relay's DPDT configuration implies that each set of three pins forms a switch with a common pin.
  • Another participant notes that applying positive voltage pulses only switches the relay on once, requiring a negative pulse to turn it off, raising the question of how to achieve single positive pulse control.
  • A suggestion is made that reversing the polarity of the voltage on the coil may be necessary for switching, but this could complicate the circuit design.
  • John expresses concern about using a 38 kHz IR receiver to control the relay, noting that it only activates for the first 14 pulses of IR light.
  • Participants discuss the potential use of a reed relay and the timing of pulses needed to effectively switch the relay.
  • One participant proposes using a flip-flop and H-bridge IC to control the latching relay, while another shares a circuit using a 555 timer to generate a pulse from an IR input.
  • John seeks clarification on modifying the proposed circuit to utilize a reed relay instead of the IR receiver.

Areas of Agreement / Disagreement

Participants express various approaches and ideas regarding the relay's operation and control methods, but no consensus is reached on a definitive solution or configuration. Multiple competing views on how to effectively use the relay and the necessary circuit components remain present.

Contextual Notes

Participants mention the need for specific pulse timings and configurations, but there are unresolved questions about the adequacy of pulse duration for switching and the implications of using different relay types. The discussion also highlights dependencies on the characteristics of the IR receiver and the relay's design.

Who May Find This Useful

Individuals interested in relay circuits, particularly those working with latching and reed relays, as well as those exploring control methods for switching loads using various input signals.

jbord39
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Hey guys. I bought this relay

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=255-1899-ND

It is supposed to operate at 11 mA. My question is, this thing has 8 pins, and I cannot find a diagram with what pin is what. Does anyone know what sort of configuration I would need just to simply turn on/off a load through the coils?

Thanks,

John
 
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jbord39 said:
Hey guys. I bought this relay

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=255-1899-ND

It is supposed to operate at 11 mA. My question is, this thing has 8 pins, and I cannot find a diagram with what pin is what. Does anyone know what sort of configuration I would need just to simply turn on/off a load through the coils?

Thanks,

John

The two pins off by themselves are the input coil. Since the switch is DPDT, each switch has 3 pins. So I'm guessing that each of the two sets of three pins forms the switch, with the middle pin the common. A little time with a DVM and your power source switching the relay back and forth will let you beep out the pinout of the switches.
 
Thanks. I am trying to use this relay to switch something on or off. I can get the coil to switch back and forth, but applying positive voltage pulses will switch it on once (any subsequent positive pulses have no effect), then require a NEGATIVE pulse to switch it off. Do you know if there is any way to cause a single positive pulse to either switch on/off the relay?

Thanks again
 
As a latching relay, you might have to reverse the polarity of the voltage on the coil to make it switch.

I have a number of these and the difficulty of reversing polarity outweighs the fact that it needs no current to hold the contacts in either position once it has switched.

EDIT: sorry, I didn't see your comment Jbord. You could use the contacts of the relay to reverse the polarity, but it would need both sets of contacts and this would not leave you with any useful contacts for your project. This would probably produce a buzzer effect as the relay would switch rapidly to each mode.
 
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Dang. What sort of setup would I need to use singular pulses to turn on or off something? I have a reed relay, a regular relay, and two latching relays (if any of these can be utilized).

The problem with the regular relays is that I am using a 38kHz IR receiver to switch the relay on/off, and the receiver innately will "turn-on" only for the first 14 pulses of the IR light (which is continuous).

I thought this would be an advantage for switching on/off a latching relay, but I did not realize that the latching relay required a negative voltage to switch.
 
Do you think this circuit could be adapted for my use?

A reed relay which is activated for about (14 pulses)*(1/38000) = 368 uS.

This relay (which is switching on and off as expected) could be used to power another circuit such as:

toggle7.gif


My question is, do you think that substituting a 368uS "push" would even give adequate time for the capacitors to charge, and therefore switch correctly? Obviously the circuit was designed for humans pushing the button, and I expect most people push down on a button for more than 368uS.

Thanks again everyone; you are awesome.
 
jbord39 said:
Dang. What sort of setup would I need to use singular pulses to turn on or off something? I have a reed relay, a regular relay, and two latching relays (if any of these can be utilized).

If you have two latching relays, it seems you could use one for the direction control (for both relays), and one for your functionality. I haven't thought it all the way through, though, so I could be wrong.

You could use a flip-flop (FF) as long as it always stayed powered, and an H-bridge IC to drive the coil of a single latching relay...
 
jbord39 said:
Hey guys. I bought this relay

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=255-1899-ND

It is supposed to operate at 11 mA. My question is, this thing has 8 pins, and I cannot find a diagram with what pin is what. Does anyone know what sort of configuration I would need just to simply turn on/off a load through the coils?
I think this is the pinout for relay. It is a DPDT:

http://media.digikey.com/pdf/Catalog Drawings/Relays/TX-PCBd-bottom1COIL.jpg

Bob S
 
Thanks guys. Any idea if that circuit could work (before I buy the components)?

Thanks again,

John
 
  • #10
This circuit uses a monostable 555 to produce a 1/2 second pulse from a brief burst of 38 KHz infra red input.
Although it was intended to drive a camera shutter, it may suit your purposes, depending on what they are.

http://dl.dropbox.com/u/4222062/IR%20rec%20and%20monostable.JPG

A caution, though. I would expect that the output of the IR receiver would need a pullup resistor of about 4.7 K to the 5 volt supply. Your IR receiver may or may not work like that.
The 7555 certainly expects a falling pulse to trigger as a monostable.

This picture is from the Australian "Silicon Chip" magazine.

To change the delay you could change the components that go to pins 6 and 7 of the 7555. Making them bigger increases the delay.
Pin 3 of the 7555 goes high for some period determined by these components and then drops to a low value again.

When your receive chip goes low and then high, how long is it before it can go low again?
 
Last edited by a moderator:
  • #11
The IR receiver can go back to 0V as soon as the signal is stopped. Example: moving my hand with fingers open triggers it each time a finger breaks the signal.

Rather than worry about using the IR receiver, I think it would really simplify the circuit to use a circuit I already have using a reed relay to switch something else on or off.

How could I modify the above circuit to just use a single toggle from the reed relay instead of the IR receiver?

Thanks so much again.
 

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