more balanced current

 

Compare the current through R8 and R9. Increase R7 to get a more balanced current. 

Trace the current paths during a cycle. One cap charges as the other discharges etc.

How does this effect the current through R7?

vary the cap sizes

 

I set the battery resistance to 2 Ohm.

Changes the cap values improves the circuit.

How can we improve the circuit?

 I disconnected the input to see what happened.

It appears I did a great job of building an oscillator. What did I do wrong OR what can be done to improve the circuit?

Vary the battery resistance and test the circuit stability.

 Add 2 Ohm internal resistance in the battery, click the battery and you find two boxes voltage and resistance. Run the sim and you see a swing in supply voltage. Increase the battery resistance to 200 Ohm.

Wow!. The supply drops to less than 8 volts and it oscillates. (motorboat)

The layout to avoid cross currents in the ground plane.

The currents in the ground plane will produce field which can aid or oppose each other, the example shows the 'proper' grounding method. 

 When examining the circuit stability current loops could become and issue.

Adding the .startup command will cause the circuit to start with 0 volts.

 

I set the scan for 2 seconds so the circuit could stabilize.

So this is what happens while the capacitors are charging.

The battery resistance is at 0 ohm. When we add the battery resistance what effect will that have?

I saw a recent post that said the bigger the caps the better. This series of post will explore that idea. 

So the idea is to look at what we have and vary the circuit to get a better response.

I put this circuit on a board and it was quite sensitive and quite unstable.

We need to consider the battery resistance. A fresh 9 volt battery may have 2 Ohms internal resistance. As it ages that may go much higher. How to look at the battery resistance will be coming shortly.

Earbud Amp with feedback ideal circuit

 This ideal circuit would be great for my earbuds IF it works as the sim does. I have some 10ma earbuds which it would be good for. Next I add a real world test.