Urgent - Circuit suddenly won't work

[kittygobeep]

I removed and restored the battery power to a fairly simple circuit that was working fine - and suddenly it will not work. The batteries, 3 new AAs, will only give about 0.6V, and the batteries heat up abnormally and very quickly.

This has happened once to me before, and that time I left the circuit overnight and the next morning it worked again. However, today I really really seriously need the circuit to work now.

Is this a common problem? Any advice at all, please?!

Thanks very much.

 

[Andrew Cowan]

You've got a short circuit somewhere - a link between the positive and 0V lines. Are there loose wires/leads/bits of metal?

The reason a circuit may work later, is batteries can recharge themselves slightly overnight, once the fault is gone.

Use a multimeter to measure the resistance between the positive and negative lines.

If you can not find the fault, a photo would help us help you.

Andrew

 

[ramasule]

The anode is connected to my pos rail
The pos rail is connected to my neg rail
The neg rail is connected to my cathode
The cathode is connected to my ....
Hey whats that burning smell and melting wires?

 

[Dippy]

Other than what Andrew has said, have you checked the PICAXE?

Without a description, schematic, decent photo or artwork (if applicable) we're wasting our time.

 

[BeanieBots]

No, it is not a common problem. Quite simply, you have a fault with your circuit.
Interestingly, 0.6v suggets the battery is either connected the wrong way around or you have a dead short.
A nice example of why we recommend batteries. If you had been using a PC power supply, you could easily find the short/error. It would be the bit glowing red and smoking. If not embedded in your eye, the chip can be found stuck to the ceiling.

As Dippy says, send us a picture, BEFORE you try to power it up again.

 

[Blue Eagle]

A nice example of why we recommend batteries. If you had been using a PC power supply, you could easily find the short/error. It would be the bit glowing red and smoking. If not embedded in your eye, the chip can be found stuck to the ceiling.

Lol, that's why you use current + thermal limited voltage regulators

 

[Andrew Cowan]

that's why you use current + thermal limited voltage regulators

Exactly - although I use a 500W 12V power supply, I regulate the voltage using an LM317 (2.5A max), and the current using a current limiting chip (5mA to 2000ma adjustable).

Andrew

 

[ramasule]

that's why you use current + thermal limited voltage regulators

Exactly - although I use a 500W 12V power supply, I regulate the voltage using an LM317 (2.5A max), and the current using a current limiting chip (5mA to 2000ma adjustable).

Andrew

Regulate the current??? I use a 600 w pc power supply with no limiting and its much easier to find/troubleshoot your circuit when you have made a mistake.

One might say the problem jumps right out at you.

 

[Dippy]

I use a TTi Bench Power Supply. I don't have to worry.

Though sometimes when I connect an LED (an LED, not a LED) I get a phone call from the National Grid asking me to check the resistor value as it is slowing down the turbines on one of the Nuke power Stations.

 

[sedeap]

To Dippy



What you plan Dippy?
Be the first man to put a PICAXE over the surface of Moon... or make a new crater in it, shooting with Picaxe sparkly propulsated?

LOL

 

[westaust55]

For what according to the heading is an urgent issue, no response with further information, advise whether comments made have helped, indication if solved and how, etc

 

[ramasule]

Dang that was you Dippy that caused stage 3 loadshed the other day?

 

[Andrew Cowan]

Regulate the current??? I use a 600 w pc power supply with no limiting and its much easier to find/troubleshoot your circuit when you have made a mistake.

One might say the problem jumps right out at you.

Before I added the current regulation, I had one test go wrong. I was trying to make a servo tester with a 555. I connected everthing up, switched it on... ...and watched as huge clouds of black smoke poured out of every crack in the servo casing. When I took it apart, I found a capacitor (ceramic, not electrolytic), had been completly destroyed. Waste of a servo, really.

Andrew

 

[ramasule]

Yes see exactally, your problem was the capacitor that lost its soul

 

[kittygobeep]

Thanks everyone - I found a short circuit, and it's working again now.

@westaust55: I needed to finish the circuit and design a load of other materials, all yesterday, and it was urgent to me that the circuit worked. The delayed response was because I was very pressed for time, and didn't have constant internet access anyway.

I do really appreciate all of your quick responses!