# Frequency measurement with counters

I'm trying to get the following circuit to work. It says to:

Connect the circuit as shown in the block diagram in Figure 2 by adding a NAND gate followed by a CD4029 connected as a decade counter. For the CD4029, connect one of the lab station’s switches so that it will reset the counter, and connect the four outputs of the counter to LEDs on the lab station.

Input a TTL signal from the signal generator that has a frequency somewhere between 2 Hz and 9 Hz and verify this frequency using the oscilloscope. Note that you will have to measure the frequency. The frequency readout of the scope will not help.

View the LED that is monitoring the 1 second pulse, and reset CD4029 counter while the frequency divider output voltage is low. Then, when the same signal goes high, verify that the CD4029 counts the signal pulses being output by the generator. When the divider signal again goes low, read the final count in the CD4029. It should be the same as the output frequency of the signal generator.

Using the function generator of the NI myDAQ, I've set the frequency to 5 Hz and connected it to one input of the NAND gate and connected the 0.5 Hz signal to the other input of the NAND gate. The output of the NAND gate is then connected to the clock input of the CD4029 counter. A switch is connected to the PRESET of the CD4029. All of the Q outputs of the CD4029 are on when the board is first powered on.

When the LED on the 1 Hz signal goes low I press the button switch and all four of the LEDs turn off. However, none of the LEDs turn back on unless I turn on and off the power supply; then all four of the Q output LEDs turn back on. The output frequency should be the same as the 5 Hz signal frequency, which means that the output of the four LEDs should be 0101, but they're all off. Can someone help me figure out what is wrong?

The waveform I'm getting at the clock input of the CD4029 looks like this:

The frequency at this point varies up to around 2 kHz on my oscilloscope.