Author Topic: Control 24v alarm siren with Moteino, using ULN2003AN?  (Read 286 times)

Lukapple

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Control 24v alarm siren with Moteino, using ULN2003AN?
« on: November 12, 2018, 04:26:36 PM »
Hi guys,
I want to control an alarm siren with Moteino, using ULN2003AN. Iím a software guy, thatís why Iím asking you for help.
Here is list of parts, that I already have:
- Siren Bosch SG 200, 12/24V - will use 24v (Data sheet: https://resource.boschsecurity.com/documents/Data_sheet_enUS_1332635915.pdf)
- ULN2003AN (Data sheet: http://www.ti.com/lit/ds/symlink/uln2003a.pdf)
- DC power supply 24v 1500mA
- Moteino 

Can you guys help me with schematics  ;)
It would be also great, if I could use same power supply to power Moteino.

Thanks!

TomWS

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Re: Control 24v alarm siren with Moteino, using ULN2003AN?
« Reply #1 on: November 13, 2018, 07:54:44 AM »
The answer to your question is, yes, the ULN2003AN will work for this application.

However, I'm curious, do you want to use the ULN2003AN because it is a through hole device and it's easier for you to wire?  Because that's what you have 'on hand' (following WIHOH design methodology)?

The reason I ask is that a simple FET will work for this application.

You don't need any power from the Moteino for the ULN2003.  The device is just a transistor driver that requires no additional power.  Tie any available GPIO to one of the ULN2003 input pins.  Connect Moteino GND to ULN2003 and 24V DC Ground.  Connect negative terminal of your VERY LOUD alarm to the corresponding output of the ULN2003. Finally, connect positive terminal of your VERY LOUD alarm to +24VDC and do this while wearing earprotectors.


Set the Motenio GPIO with the following code:

Code: [Select]
#define VERYLOUD_ALARM_PIN  x
...
   digitalWrite(VERYLOUD_ALARM_PIN,LOW);  // do this BEFORE setting pinmode
   pinMode(VERYLOUD_ALARM_PIN,OUTOUT);
...
   // WAKE UP Neighborhood!
   digitalWrite(VERYLOUD_ALARM_PIN,HIGH);

Lukapple

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Re: Control 24v alarm siren with Moteino, using ULN2003AN?
« Reply #2 on: November 13, 2018, 04:37:55 PM »
Thanks for your answer Tom.
Yes, I wanted to use ULN2003AN, because I have them "on hand" :) Well I think that I also have few MOSFETs on hand, thanks for the hint.
Do I have to use any pull-down resistors with ULN2003AN or MOSFET? (I've noticed pull-down resistor in this sample schematics).

Any suggestions how to use same power supply(24v) that will be used to power siren, to power Moteino? Which 24V to 3.3-9V converter should I use and how to wire it to siren power supply?

Lukapple

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Re: Control 24v alarm siren with Moteino, using ULN2003AN?
« Reply #3 on: January 27, 2019, 02:01:55 PM »
Final product. It works perfect  ;)