7 reasons For Circuits Not Working

7 reasons For Circuits Not Working

The most frustrating moment is when you have spent so many hours to make a circuit and finally it isn't working! So here we suggest some tips to debug your circuit in a better way!

1. Bad Connection Or No Connection

• You left out a wire or connection. It is easy to leave out a connection. Double check all connections, and then triple check.
• There is a short. After soldering a circuit, Use a magnifying glass to check for solder joints or frayed wire ends that could be shorting.

2. Wrong Connection

You are usually looking at the top of the circuit board and soldering the bottom of the circuit board using a top view schematic. It is easy to get visually turned around. When there is a wrong connection, this can require a new visualization of the situation. To avoid the same perceptual errors, So turn the schematic and the circuit board upside down from the way you was looking at it and then check again to see that all the connections are valid. Perceiving from a different point of view can reveal flaws.

3. Noise In The Circuit Or Near It

• Avoid running inputs next to outputs. Pulsating outputs such as PWM can transfer through induction to inputs and create an erratic circuit. Amplifiers and micro controllers are especially sensitive.
• A really long input wire can act as an antenna and pick up noise. In that case you can use a grounded, shielded cable.
• When you can, it is a good idea to have two power supplies that share a common ground. One for the control circuit and another one for the motors, servos, or other noisy loads. 
• With logic circuits and micro controllers, leaving a floating input can render your circuit useless. Inputs should be grounded or connected to V+ through a 4.7 to 10K ohm resistor. Otherwise the input can act as an antenna and pick up spurious signals from house hold AC or other sources.

4. Bad Power Supply

Make sure your power supply is providing power to the right places and is not being over strained. If the power supply is inadequate to the task, it can drop in voltage and reset micro controllers or make other components erratic. Batteries, under no load, can be measured and have the proper voltage, but when connected to the circuit, the voltage can drop enough to make the circuit useless. Measure battery voltage under the actual circuit load.

A badly filtered power supply can also create noise and cause problems with sensitive circuits. A large value capacitor 20- 200 uf near the power supply can reduce the voltage ripple.

5. Overheating
If the circuit is on and a transistor, resistor, or IC is too hot to touch and you cannot keep your finger on it for several seconds, something is wrong. Such components can normally operate somewhat warm--but not hot. You need a higher wattage resistor or you are overloading your transistor or IC with too much current.

6. Wrong Design Assumptions
With experimental circuits we make a lot of assumptions. Sometime we can get away with it sometimes not. You might have underestimated the current that small servos and motors require resulting in power supplies overheating or shutting down.
If size is not an issue, allow more room than you think you need to fit the main components. Packing too tight can make soldering difficult and slow and increase the chance of noise problems between components. 

It is tempting to design as if the circuit is going to work first time every time. That is rarely the case. A better way is to design with the assumption you will have to debug. Design in connection points such as pins, sockets, or temporary wires that give you access to measure current and voltage on the actual circuit.

7. Bad Components
With today's high quality mass produced electronic components, new components that don't work are extremely rare. However it is fairly easy to overheat a component while soldering and damage it. Transistors, diodes, ICs, and to a lesser degree, resistors and capacitors are susceptible to overheating while soldering.

Make sure about these things when you are debugging a circuit!