Please help need to fire relay with IC

In summary, the conversation is about a circuit built with a cd4017 IC that works with a small LED, but not with a larger load like a relay. The suggestion is to use a transistor instead, preferably one rated for the desired current and load. It is also advised to use a reverse biased diode to prevent damage to the switching device. Additionally, it is mentioned that turning things on in stages may be necessary due to the control IC not providing enough current.
  • #1
Sightsound
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Hi guys I'm new here and need map some help. I have built a simple circuit with a cd4017 IC. The circuit works perfectly and has led connected to it. However I want to connect much larger load to it. A relay is the obvious answer but I'm not getting enough current from the IC to fire the relay. I tried using a triac but the triac latches and I'm led to believe that this is because it's a dc load, the relay. I'm stuck now any suggestions welcome please.
 
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  • #2
a transistor would be a better/easier way to go unless you were switching more that say 10A

attachment.php?attachmentid=72084&stc=1&d=1407801780.gif


OK I have drawn this one ... still switching a LED
The 2N3904 transistor will switch a couple of 100 mA

choose a transistor rated for a current and load you want to switch

for high currents, you could replace the LED and 1k resistor with a relay ... don't forget to add a reverse biased diode (1N4001) across the relay coil, else you will kill the transistor

Dave
 

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  • #3
More often than not you will find that you have to turn things on in stages because the control IC doesn't provide enough current to drive the switching device. Davenn's suggestion is good. I just wanted to add that the reverse biased diode he mentioned is often called a "flyback diode" and it is sometimes included inside the relay itself. Check your datasheet for your relay to see if it has a diode.
 

What is a relay and how does it work?

A relay is an electrically operated switch that can be controlled by a small electrical signal. When the signal is applied, it causes the relay to switch on or off, allowing or interrupting the flow of current to another circuit.

What is an IC and how does it relate to firing a relay?

An IC, or integrated circuit, is a small electronic device that contains multiple components such as transistors, resistors, and capacitors on a single chip. It can be used to control the firing of a relay by providing the necessary electrical signal to activate it.

What are the steps to fire a relay with an IC?

The steps to fire a relay with an IC may vary depending on the specific circuit and components used, but generally, it involves connecting the IC to a power source, connecting the relay to the appropriate pins on the IC, and programming the IC to send the necessary signal to activate the relay.

What are some common problems encountered when trying to fire a relay with an IC?

Some common problems may include incorrect wiring or connections, insufficient power supply, or incorrect programming of the IC. It is important to double-check all connections and troubleshoot any potential issues to ensure successful firing of the relay.

Are there any safety precautions to keep in mind when working with relays and ICs?

Yes, it is important to follow proper safety precautions when working with any electronic components. This may include wearing appropriate protective gear, handling components with care, and disconnecting power sources before making any changes or adjustments to the circuit.

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