We've been working on trying to get the circuit attached working for awhile now, and have had a miserable time troubleshooting.
circuit explanation
"The LH half of the circuit removes the load from the battery when its voltage has fallen too low.
The RH side controls when the battery charges, ie. when the solar panel is giving a higher voltage that the battery, and when the battery voltage is below nominal.
This is a description of the RH side, but both sides are similar. The LM393 senses the battery voltage because its inverting terminal is set at 0.7V (the voltage drop across the 1N4148), but the voltage at the non-inverting input (pin2) will depend on the battery voltage, depending on the setting of VR1. With VR1 set so that pin2 is at 0.7V with a battery voltage of 13.8V, then output pin1 will go high. (In my view that’s a bit high because it is the voltage at which the battery should switch off or float charge – I would have chosen 12.8V). When pin1 goes high and the battery goes on charge its voltage rises. That would normally make pin1 go low again so the resistor RX2 provides positive feedback to give some hysteresis, to prevent that. Now let’s look at it when the battery volts are lower and pin1 goes low.
The CD4011 is a quad NAND gate (not an AND gate as shown by the symbol). In each half of the circuit 2 gates are wired as a bistable by the two 100K resistors, ie. either gate of the bistable can be on at any time, but not both together.
Pin1 being low will put a negative pulse on to pins 5/6 of the CD4011 and turn on the bottom gate (pin4 low) and turns off the top gate (pin3 high). The BC3904 switches on via the 1K and its collector goes low. That forward- biases the P-MOS and allows the battery to charge. With the output pin3 low, the N-MOS is switched off and the dump load disconnected.
The LH side works in a similar manner.
The two .1µF caps are not necessary – there is enough swing on the outputs of the LM393s to allow them to be wired straight into the gate inputs. D2 is there to isolate the sections of the supply line while the system is being set up.
D3 is to isolate the solar panel when its output is low on a dark day, the battery is low, and the P_MOS has switched on.
-PEBE- "
circuit overview and conditions
conditions - see led conditions attachment
video - **broken link removed**
**broken link removed**
Testing Procedures
You can set it up with two variable supplies, like this.
Assemble everything and use a 1K resistor as the temporary main load.
Wire your first power supply in place of the solar panel and set it to 10V permanently.
Wire your second power supply up in place of the battery and set it to 14V. This is the supply to adjust as stated.
1. Set PS for 14V. Adjust VR2 for minimum resistance. LED-1 will be off.
2. Check that LH P-MOS is switched on (there is voltage across the 1K resistor)
3. Reduce PS to 11V
4. Slowly increase VR2 until LED just turns on.
5. Check for no volts across 1K resistor.
That's the LH side set up. Now for the RH side.
1. Leave PS set to 11V
2. Set VR1 to its max resistance. LED-2 will come on.
3. Check collector of 2N3904 is at about 0V (P-MOS is turned on)
4. Increase PS to 13.6V
5. Slowly adjust VR1 so that LED-2 just turns off.
6. Check that drain of N-MOS is at about 0V
-PEBE-
video - **broken link removed**
video - **broken link removed**
video - **broken link removed**
My partner and I love the potential function of this circuit, but we've had such a difficult time getting it to work, that we are at the point where we'll be forced to attempt another circuit with similar functions. We're willing to do what it takes to get this thing working if anyone thinks they can help. We're also somewhat okay at recording videos for troubleshooting so if you need more information we can make more videos. Also skype is a possibility!
Thanks again eletrotech community
circuit explanation
"The LH half of the circuit removes the load from the battery when its voltage has fallen too low.
The RH side controls when the battery charges, ie. when the solar panel is giving a higher voltage that the battery, and when the battery voltage is below nominal.
This is a description of the RH side, but both sides are similar. The LM393 senses the battery voltage because its inverting terminal is set at 0.7V (the voltage drop across the 1N4148), but the voltage at the non-inverting input (pin2) will depend on the battery voltage, depending on the setting of VR1. With VR1 set so that pin2 is at 0.7V with a battery voltage of 13.8V, then output pin1 will go high. (In my view that’s a bit high because it is the voltage at which the battery should switch off or float charge – I would have chosen 12.8V). When pin1 goes high and the battery goes on charge its voltage rises. That would normally make pin1 go low again so the resistor RX2 provides positive feedback to give some hysteresis, to prevent that. Now let’s look at it when the battery volts are lower and pin1 goes low.
The CD4011 is a quad NAND gate (not an AND gate as shown by the symbol). In each half of the circuit 2 gates are wired as a bistable by the two 100K resistors, ie. either gate of the bistable can be on at any time, but not both together.
Pin1 being low will put a negative pulse on to pins 5/6 of the CD4011 and turn on the bottom gate (pin4 low) and turns off the top gate (pin3 high). The BC3904 switches on via the 1K and its collector goes low. That forward- biases the P-MOS and allows the battery to charge. With the output pin3 low, the N-MOS is switched off and the dump load disconnected.
The LH side works in a similar manner.
The two .1µF caps are not necessary – there is enough swing on the outputs of the LM393s to allow them to be wired straight into the gate inputs. D2 is there to isolate the sections of the supply line while the system is being set up.
D3 is to isolate the solar panel when its output is low on a dark day, the battery is low, and the P_MOS has switched on.
-PEBE- "
circuit overview and conditions
conditions - see led conditions attachment
video - **broken link removed**
**broken link removed**
Testing Procedures
You can set it up with two variable supplies, like this.
Assemble everything and use a 1K resistor as the temporary main load.
Wire your first power supply in place of the solar panel and set it to 10V permanently.
Wire your second power supply up in place of the battery and set it to 14V. This is the supply to adjust as stated.
1. Set PS for 14V. Adjust VR2 for minimum resistance. LED-1 will be off.
2. Check that LH P-MOS is switched on (there is voltage across the 1K resistor)
3. Reduce PS to 11V
4. Slowly increase VR2 until LED just turns on.
5. Check for no volts across 1K resistor.
That's the LH side set up. Now for the RH side.
1. Leave PS set to 11V
2. Set VR1 to its max resistance. LED-2 will come on.
3. Check collector of 2N3904 is at about 0V (P-MOS is turned on)
4. Increase PS to 13.6V
5. Slowly adjust VR1 so that LED-2 just turns off.
6. Check that drain of N-MOS is at about 0V
-PEBE-
video - **broken link removed**
video - **broken link removed**
video - **broken link removed**
My partner and I love the potential function of this circuit, but we've had such a difficult time getting it to work, that we are at the point where we'll be forced to attempt another circuit with similar functions. We're willing to do what it takes to get this thing working if anyone thinks they can help. We're also somewhat okay at recording videos for troubleshooting so if you need more information we can make more videos. Also skype is a possibility!
Thanks again eletrotech community
Last edited: