HI,
I made a circuit that worked very well on a 9V battery. The only problem was it only lasted 2days before the battery went flat and the circuit would not operate properly.
The circuit uses 6mA at rest and about 100mA when the relay energises which remains like this for 2hrs. (How many mAH is a typical 9v battery?)
Parts in my circuit
1A Regulator – 7805
14-stage ripple-carry binary counter/divider and oscillator - 4060
5vDC relay
Various resistors/capacitor/a transistor etc.
[My circuit is a 2hr timer. It keeps a relay energised for 2hrs when a push to make is hit]
Anyway I had the bright idea of running the circuit off the mains (240v ac), using a transformer and rectifier circuit.
Im new to electronics, I have never used a transformer before and I’m not sure if its working correctly. I believe the transformer is getting too hot!
I say this because it seems real hot to the touch (but maybe that’s normal). But it smells bad too. Also the brownish lacquer on the outer metal parts seemed to have melted. Plus I can here a buzzing sound too.
On the box of my transformer it says Primary 0-230v. Secondary 9-0-9v 250mA
I wired the primary winding to the mains. Brown to Brown (live). Blue to Blue (Neutral).
The secondary I used the black wire and ONLY 1 white 1 (and just cut the other white wire off) to a bridge rectifier (which was a W08).
Please can someone help – why is the transformer so hot? Is this normal? Do they need Ventilation? The whole thing is in a sealed biscuit tin.
(by the way my circuit works fine off the transformer - its just so damn hot. Im very worried about it. Its unplugged now.)
I have justed worked out the buzzing was from the lid of the box I made touching the transformer. It does not buzz with lid off.
Thanks.
I made a circuit that worked very well on a 9V battery. The only problem was it only lasted 2days before the battery went flat and the circuit would not operate properly.
The circuit uses 6mA at rest and about 100mA when the relay energises which remains like this for 2hrs. (How many mAH is a typical 9v battery?)
Parts in my circuit
1A Regulator – 7805
14-stage ripple-carry binary counter/divider and oscillator - 4060
5vDC relay
Various resistors/capacitor/a transistor etc.
[My circuit is a 2hr timer. It keeps a relay energised for 2hrs when a push to make is hit]
Anyway I had the bright idea of running the circuit off the mains (240v ac), using a transformer and rectifier circuit.
Im new to electronics, I have never used a transformer before and I’m not sure if its working correctly. I believe the transformer is getting too hot!
I say this because it seems real hot to the touch (but maybe that’s normal). But it smells bad too. Also the brownish lacquer on the outer metal parts seemed to have melted. Plus I can here a buzzing sound too.
On the box of my transformer it says Primary 0-230v. Secondary 9-0-9v 250mA
I wired the primary winding to the mains. Brown to Brown (live). Blue to Blue (Neutral).
The secondary I used the black wire and ONLY 1 white 1 (and just cut the other white wire off) to a bridge rectifier (which was a W08).
Please can someone help – why is the transformer so hot? Is this normal? Do they need Ventilation? The whole thing is in a sealed biscuit tin.
(by the way my circuit works fine off the transformer - its just so damn hot. Im very worried about it. Its unplugged now.)
I have justed worked out the buzzing was from the lid of the box I made touching the transformer. It does not buzz with lid off.
Thanks.
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