Transformer Question

[firealarmfreak]

Hey everybody,

I have a 160 in-one-electronic project kit. I am using the 9 volt relay on the kit to create a latching circuit.

This board is used as a homemade fire alarm control panel im currently constructing.

I have 2 transformers connected to it. 1 18 volt DC 1 amp for the bell/strobe and 1 9 volt DC 1 amp for the relay. (it is a 9 volt dc relay im using)

Everything including the transformer for the bell/strobe works fine EXCEPT my relay transformer.

My relay transformer keeps burning out for some reason.

I was using a 9 volt dc 210 mA transformer for like a month or so working just fine, then one day, i used it, it was fine, a few hours later the relay stopped working and i looked and the transformer had melted.

I right away disconnected it and threw the transformer into the garbage.

I then put a 9 volt battery to the relay and it worked, but not with the transformer.

Then, i went to an electronic componenet store and baught a new transformer. Its a 9 volt dc 1 amp transformer.

When i connected it the relay worked again, until now. Now suddenly again this one randomly burned out. It was fine all day today i was usinmg it and then suddenl the relay wouldnt work and i found out that the relay worked on a 9 volt battery, but not the transformer.

I tried the transformer on a 9 volt dc motor, didnt work, but it worked on a 9 volt battery.

This transformer is only a week old.

It seems odd that the bell/strobe one is always fine, but the relay one always dies.

Does anybody know why the transformers are burning out?

Thanks.

Chris.

 

[mwtheplumber]

Just a thought, maybe wrong but have you got a diode across the relay to protect against back emf?

 

[Hero999]

The 9V transformer is not just a transformer, it's a propper little power supply. Transformers just give out AC. The power supply definitely uses a transformer to reduce the mains voltage but it also has a rectifier, smoothing capacitor to convert the AC to DC and possibly a regulator which keeps the output voltage the same even if the input varies.

Did you pay good money for your 9V power supply or was it a cheapy?

The 9V power supply might have not been able to provide enough current to power/start the DC motor. If the power supply has a current limiter in it, it might cut off the power when you connect your motor as it probably tries to pull 10A.

Is there plenty of ventilation around your power supply?

Could you please post a copy of the circuit so we can check that there's nothing wrong?

 

[firealarmfreak]

Diagarm *requested*

This is the diagarm of my current set up.

Any questions and or problems reading it, please let me know in a reply.

**broken link removed**

 

[audioguru]

Wires are all over the place.

 

[Hero999]

Where's it gone?

It was there yesterday.

Please don't show all the wires and everything, just show how everything is electrically connected. Using proper symbols for the components, aslo makes things much easier to understand.

Ataching the schematic rather than uploading it to another file hosting server is also a good idea as the tread will still make sense if the other site goes down.