DC Motor in parallel with a Voice Recorder Playback Module

Thread Starter

isagollo

Joined Feb 20, 2021
15
I’ve build a circuit using 3V(2x 1.5Volts AA battery)connected in parallel with a ISD1820 Voice Recorder Playback Module with Speaker in parallel with a DC Motor and a Red Led. When I turn the circuit on the LED brightness reduces and the recorded audio in the speaker doesn’t play. What should I do? I tried putting a capacitor in parallel but I just get some noise sounds no the message I recorded. Can I someone give me a hand on this circuit?
 

SamR

Joined Mar 19, 2019
3,400
Do you have any specs on the motor? Make, Model, Voltage, etc? Looks like it is drawing more power than the batteries can supply for the entire circuit.
 

KeithWalker

Joined Jul 10, 2017
1,778
Does the voice recorder module work if you disconnect the motor?
SamR is probably right. Are you using a spring contact battery holder? The contacts on those are relatively high resistance, so when the motor is running, the voltage getting to the voice module will be too low for it to work correctly. The motor will also generate a lot of electrical noise on the supply which will interfere with the operation of the voice module too.
I suggest that you use a single Li-Ion cell with two sets short wires soldered directly to the terminals. One set for the motor and one set for the recorder.
 

Thread Starter

isagollo

Joined Feb 20, 2021
15
Does the voice recorder module work if you disconnect the motor?
SamR is probably right. Are you using a spring contact battery holder? The contacts on those are relatively high resistance, so when the motor is running, the voltage getting to the voice module will be too low for it to work correctly. The motor will also generate a lot of electrical noise on the supply which will interfere with the operation of the voice module too.
I suggest that you use a single Li-Ion cell with two sets short wires soldered directly to the terminals. One set for the motor and one set for the recorder.
 

Thread Starter

isagollo

Joined Feb 20, 2021
15
Does the voice recorder module work if you disconnect the motor?
SamR is probably right. Are you using a spring contact battery holder? The contacts on those are relatively high resistance, so when the motor is running, the voltage getting to the voice module will be too low for it to work correctly. The motor will also generate a lot of electrical noise on the supply which will interfere with the operation of the voice module too.
I suggest that you use a single Li-Ion cell with two sets short wires soldered directly to the terminals. One set for the motor and one set for the recorder.
It works. When I remove the dc motor fan, I can hear the message recorded in the module. But when adding the fan, the module doesn’t start. When I put a capacitor in parallel, I’ve heard some noise sounds in the voice message but not as good. What can I do? Should I try to use resistor in series with the dc motor? Capacitors? I’ve read sth about ptc fuses too but idk. Looking for a simpler solution
 

SamR

Joined Mar 19, 2019
3,400
Minimum voltage on the motor is 3V. The 2 AA bateries in series will provide 3V briefly under load. The motor draws 500mA or 1/2A and the new battery can only provide @ 500mA for maybe 3 hours but in order to do so the voltage drops off steeply. What you are doing is overloading the battery. The sound module is rated for 3.3V so you need a better 3V power supply. You can try using 2 new D cell batteries instead of the AA but once again they drop in voltage quickly at that current draw. You need a better steady supply of power.

Edit: adding a fan to the motor greatly increases the load and thus the current draw.
 
Last edited:

MisterBill2

Joined Jan 23, 2018
8,723
We don't know the current draw of the module, but the claimed half-amp draw of the motor will load down those two AA batteries to much less than three volts almost instantly. If you need a motor that powerful you will nrrd more battery capacity.
 

KeithWalker

Joined Jul 10, 2017
1,778
It works. When I remove the dc motor fan, I can hear the message recorded in the module. But when adding the fan, the module doesn’t start. When I put a capacitor in parallel, I’ve heard some noise sounds in the voice message but not as good. What can I do? Should I try to use resistor in series with the dc motor? Capacitors? I’ve read sth about ptc fuses too but idk. Looking for a simpler solution
Obviously your power source is not suitable for this application. I already gave you a solution. If you must use alkaline batteries, use larger ones with the wires soldered directly to the batteries in the same way I suggested with a Li-Ion cell.
 

MisterBill2

Joined Jan 23, 2018
8,723
Obviously your power source is not suitable for this application. I already gave you a solution. If you must use alkaline batteries, use larger ones with the wires soldered directly to the batteries in the same way I suggested with a Li-Ion cell.
Soldering directly to a battery usually melts the seals enough to greatly reduce the battery life .
 

Audioguru again

Joined Oct 21, 2019
3,172
New Name-Brand AA alkaline batteries will work until the battery holder melts.
Very cheeep AA "super-heavy-duty" batteries produce very little power and for only a short time.
 

peterdeco

Joined Oct 8, 2019
356
We've encountered this problem many times. What we do is use 2 separate 3V battery packs, one for the ISD chip, the other for the motor. Common negative ground on the battery packs and the ISD and motor. The switch connects to the battery packs common negative and supplies negative to both the ISD and motor. One of the positive leads on the battery pack connects to motor, other to ISD. We also put a 1N4148 diode and 10uF cap across the motor.
 

sghioto

Joined Dec 31, 2017
2,360
You could try using three batteries (4.5volts) to give the motor a little more kick at startup. The ISD1820 is rated up to 5 volts.
 

Thread Starter

isagollo

Joined Feb 20, 2021
15
If I use x1 lithium battery (3.7V) model 18650 as power supply to my circuit what should be the resistor value in series with the dc motor to operate at 3V - 0.5A? Will it make the ISD1820 work?
 

SamR

Joined Mar 19, 2019
3,400
The motor is rated for 3-6VDC so a resistor is not needed. What is needed is a more powerful power supply. Not just the voltage but also the mAH capacity to drive the circuit. The suggestion of dual power supplies is excellent advice, one for the motor and one for the sound module and LED.
 

KeithWalker

Joined Jul 10, 2017
1,778
If I use x1 lithium battery (3.7V) model 18650 as power supply to my circuit what should be the resistor value in series with the dc motor to operate at 3V - 0.5A? Will it make the ISD1820 work?
The datasheet states that the ISD1820 power requirement is 2.4 to 5.5 V which is ideal for a single Li-ion cell.
The 18650 capable of supplying enough current for both devices. Wire each device to the battery using a separate pair of wires. Connect a 10uF capacitor and a diode directly across the motor terminals.
 

Thread Starter

isagollo

Joined Feb 20, 2021
15
Hi, everyone!

It worked! Thank you all for helping me out in this project. I'd like some tips to choose the right Li ion battery capacity. How do I choose between the options? 1000mAh, 1800mAh, 2000mAh, 8800mAh, 128000mAh?
 

Audioguru again

Joined Oct 21, 2019
3,172
A mAh rating for an 18650 Li-Ion cell more than 3600 is fake and is a rip-off.
ebay sell many rated at 9800mAh, a review tested some and found them to measure 500mAh and costed more than a Name-Brand at 3600mAh.

The higher is the mAh then the longer a battery charge will power your device.

A resistor in series with a motor might prevent it from starting to run.
 
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