Voltage drop: Circuit to control fans and leds

[Danirov]

Hi everyone. Can you help me with this circuit I am working on, please?. (Image 1)

It consists of a TP4056 charger/controller connected to a 3.7v/1.4Ah Li-Ion battery to supply a low battery indicator and a load (3 leds + 2 fans) through a MT3608 Step Up to raise voltage from 3.7v to 9v. When the TP4056 is charging the battery through the USB port, the load is disconnected by the P-Mosfet.

PROBLEM: Voltage drops significantly when the load is connected.

Test1: Circuit without Debouncing/Load connected:
Voltage drops from 3.68v to 3.46v (image 2).
Low Battery Indicator: Blinks.

Test2: Circuit with Debouncing/Load connected:
1) Debouncing Circuit: The voltage drops to 2.19v at the output of the Smichtt Trigger, therefore it isn't possible to energize the Step Up and the rest of the circuit.
2) Low Battery Indicator: Blinks when switch is pressed.

Test3: Circuit with Debouncing/Load disconnected:
1) Debouncing Circuit: Works fine (image 3).
2) Low Battery Indicator: Doesn't blink when the switch is turned ON/OFF.

Is there something that I am forgetting to put in the circuit so the voltage is dropping?
I would suppose that the problem is at the DC/DC conversion of the Step Up, but everything is meeting its requirements (Vin:2v-24v/Imax: 2A).

My system details:
Power consumption: 1.702W
Low Bat Indicator: (0.037W, 3.7v/0.01A)
Load: 2 Fans (1.44W, 9v/0.16A), 3 Leds (0.059W, 2.92v/0.02A).
Debouncing Circuit based on a Schmitt Trigger 74HC14 (Vin:2-6v/Vout:2-VCC, VCC and GND connected to battery line).

[HarryA]

When the switch is closed in the debouncing circuit the input to the inverter is a logic 0 and the output a logic 1.

Current flows from the battery supply of the inverter to its output. But the absolute maximum current rating for the output of a 74HC14 is only 24 ma.

Do you really need a debouncing circuit?    I wonder if you could replace the mosfet and debouncing circuuit with a 3 position switch;  An On-Off-On. If not you may need a transistor between the inverter and the load. But you get a lost of 0.5 or 0.7 volts.

Also the 100mfd capacitors are quite large for you circuit; charging the one through 2000 ohms will take awhile. Perhaps 1.0 mfd?

[G_i_o]

On 7/24/2020 at 11:10 PM, Danirov said:

Hi everyone. Can you help me with this circuit I am working on, please?. (Image 1)

It consists of a TP4056 charger/controller connected to a 3.7v/1.4Ah Li-Ion battery to supply a low battery indicator and a load (3 leds + 2 fans) through a MT3608 Step Up to raise voltage from 3.7v to 9v. When the TP4056 is charging the battery through the USB port, the load is disconnected by the P-Mosfet.

PROBLEM: Voltage drops significantly when the load is connected.

Test1: Circuit without Debouncing/Load connected:
Voltage drops from 3.68v to 3.46v (image 2).
Low Battery Indicator: Blinks.

Test2: Circuit with Debouncing/Load connected:
1) Debouncing Circuit: The voltage drops to 2.19v at the output of the Smichtt Trigger, therefore it isn't possible to energize the Step Up and the rest of the circuit.
2) Low Battery Indicator: Blinks when switch is pressed.

Test3: Circuit with Debouncing/Load disconnected:
1) Debouncing Circuit: Works fine (image 3).
2) Low Battery Indicator: Doesn't blink when the switch is turned ON/OFF.

Is there something that I am forgetting to put in the circuit so the voltage is dropping?
I would suppose that the problem is at the DC/DC conversion of the Step Up, but everything is meeting its requirements (Vin:2v-24v/Imax: 2A).

My system details:
Power consumption: 1.702W
Low Bat Indicator: (0.037W, 3.7v/0.01A)
Load: 2 Fans (1.44W, 9v/0.16A), 3 Leds (0.059W, 2.92v/0.02A).
Debouncing Circuit based on a Schmitt Trigger 74HC14 (Vin:2-6v/Vout:2-VCC, VCC and GND connected to battery line).

Wow, for the fans you need to draw more power externally or as mentioned above , build in a power enhancer (easiest way to implement a power transistor).