This 60MHz bandwidth dual-trace battery powered oscilloscope/multimeter is quite the buy at around $550. The order was made with Morton Controls, and I had it in-hand 😉 in two days:
The manual can be found at the Hantek Site. We use the scope to compute power consumption by multiplying voltage waveforms by current waveforms. Traces (16384 samples) are stored onto a USB thumb-drive (NOTE: Not all thumb-drives will work, keep trying different ones – this appears to be the same issue that my Rigol scope has) for import into Excel (or gnumeric/open office, if you’re into FOSS). To compute the power (Joules), you then need to multiply the number of samples by the (scope) sample interval to determine how many micro/milli/nano-seconds you’re integrating for (since the CSV file doesn’t contain time information, only sample data). It turns out, the sample rate is dependent on the horizontal time-base selected; and the manual doesn’t tell you what those rates are.
Sooo.. I had to determine the rates empirically. To determine the scope sampling interval, I applied square waves of known frequencies at each time-scale, and recorded the traces. I then counted the number of lines (rows) in the CSV file that corresponded to a single cycle of the input frequency. I then applied the following:
Sample frequency Equation:
Sf = Calculated sample frequency (in Hz); the sample period is 1/Sf.
Wf = Input waveform frequency (in Hz)
Wp = Wave period (samples) counted from CSV file (1 set of high + low values)
Sf = 1/((1/Wf)/Wp)
Time/div Sample Rate Sample Interval
——- ———– —————
50ms 22.5 or 25 kHz (??)50 microseconds (???)
20ms 50 kHz 20 microseconds
10ms 100 kHz 10 microseconds
5ms 200 kHz 5 microseconds
2ms 500 kHz 2 microseconds
1ms 1 MHz 1 microsecond
500us 2 MHz 500 nanoseconds
200us 5 MHz 200 nanoseconds
100us 10 MHz 100 nanoseconds
50us 20 MHz 50 nanoseconds
20us 50 MHz 20 nanoseconds
10us 100 MHz 10 nanoseconds
5us 250 MHz 4 nanoseconds
1us 250 MHz 4 nanoseconds
500ns 250 MHz 4 nanoseconds
100ns 250 MHz 4 nanoseconds
10ns 250 MHz 4 nanoseconds
NOTE: On timebase rates longer than 50ms/division, the Hantek would NOT store a CSV file; the error message “Invalidate Data” was observed.
The sample period for the 50 ms/division is not too accurate since the 10Hz square wave I used had a +/- 1Hz uncertainty. I thought about building a couple of decade dividers (7490’s) and driving it with a higher frequency, but I’ll leave that up to you, if you need it.
The CSV file produced has two “header” lines, followed by the data sample lines. The first line:
Is 1/the_timebase_used (100 = 10ms/div, 2000000 = 500ns/div, etc). The line:
Specifies the number of sample lines in the file (usually 16384). Each sample line following consists of three comma separated values. Only the first value is useful, the other two are always zero.
A couple of other things: The Hantek has a maximum (1X) volts/division of 5 volts. This means for a 1X probe, the maximum voltage is 40 volts peak to peak (400 volts for a 10X probe). Morton Controls sells 100X probes; I recommend buying one or two.
For a portable, battery powered, isolated ground instrument, it’s hard to beat.