The project is a bullet counter for an airsoft rifle. Got a G36C rifle for fun, and inspired by Aliens I wanted to have a rifle with a bullet counter too! Though my little project came across a little snatch regarding power consumption. Wondering if anyone can shed light into the subject.
I've put together the following components:
- IR Emitter and sensor to detect bullet leaving barrel
- 74HC14N to stabilize IR sensor's trigger and send TTL signal to counter
- counter circuit 74LS90 and 74LS47 (times 3 digits) to drive 7 segment LED display
- 5V regulator to take power from 8.4v main battery pack
**broken link removed**
The simple 5v power supply that I used, power drawn from the main battery which drives a motor when a shot is fired
**broken link removed**
IR sensor, pin 2 of the 74HC14N is the counter's input
**broken link removed**
The LED counter consist of:
R1-R7 7 470 Ohm 1/4 Watt Resistor
U1 1 74LS90 TTL BCD Counter IC 7490,74HC90
U2 1 74LS47 TTL Seven Segment Display Driver IC
The circuit worked great. Problem comes when I fire a shot and power is drawn from the main battery from a power hungry motor, the load drops just enough to render the circuit useless. The display turns off or comes back with a random number.
An attempt to make things work I disconnected the 5v regulator and put together 4 Ni-Cad batteries to drive the counter unit, but as it turns out the circuit consumes quite a lot of power and the tiny Ni-Cad battery pack ran flat in 10 minutes.
I wanted to ask for any suggestions as to what I can do to make everything work.
- Shall I hook the main battery (plus 5v regulator) and the Ni-Cad in parallel with diodes?
- Would the LED be the ones that are draining power? Should I take the power from the main battery instead and let the Ni-Cad power the chips?
- Is there a way to find out why my circuit is eating up so much power?
It's rather surprising that the circuit would use so much power. I can actually feel the 74LS47 and the 74LS90 being warm during operation. Considering that these chips are supposed to be low power, I found it kind of strange, but being a novice I don't know how to check for power consumption.
That's it! Hope anyone can shed light into my silly little project. Thanks in advance. [/img]
I've put together the following components:
- IR Emitter and sensor to detect bullet leaving barrel
- 74HC14N to stabilize IR sensor's trigger and send TTL signal to counter
- counter circuit 74LS90 and 74LS47 (times 3 digits) to drive 7 segment LED display
- 5V regulator to take power from 8.4v main battery pack
**broken link removed**
The simple 5v power supply that I used, power drawn from the main battery which drives a motor when a shot is fired
**broken link removed**
IR sensor, pin 2 of the 74HC14N is the counter's input
**broken link removed**
The LED counter consist of:
R1-R7 7 470 Ohm 1/4 Watt Resistor
U1 1 74LS90 TTL BCD Counter IC 7490,74HC90
U2 1 74LS47 TTL Seven Segment Display Driver IC
The circuit worked great. Problem comes when I fire a shot and power is drawn from the main battery from a power hungry motor, the load drops just enough to render the circuit useless. The display turns off or comes back with a random number.
An attempt to make things work I disconnected the 5v regulator and put together 4 Ni-Cad batteries to drive the counter unit, but as it turns out the circuit consumes quite a lot of power and the tiny Ni-Cad battery pack ran flat in 10 minutes.
I wanted to ask for any suggestions as to what I can do to make everything work.
- Shall I hook the main battery (plus 5v regulator) and the Ni-Cad in parallel with diodes?
- Would the LED be the ones that are draining power? Should I take the power from the main battery instead and let the Ni-Cad power the chips?
- Is there a way to find out why my circuit is eating up so much power?
It's rather surprising that the circuit would use so much power. I can actually feel the 74LS47 and the 74LS90 being warm during operation. Considering that these chips are supposed to be low power, I found it kind of strange, but being a novice I don't know how to check for power consumption.
That's it! Hope anyone can shed light into my silly little project. Thanks in advance. [/img]