$23 Fnirsi-138 Pro Vs. $25 DSO138 Oscilloscopes (4K)

My first reaction is wow! It is small, battery powered. Comes with an optional battery and probe for $23. After I uploaded I connected both to my frequency generator and found that both respond about the same across the range from 0 Hz to 400 kHz, but the Fnirsi is more susceptible to freaking out from RFI. Not sure if it's the cheap probe or other. Will investigate. Both give you a useful (but not totally accurate) from the rated top end of 200 kHz up to 400 kHz.

I paid $25 for the original DSO 138 (no battery, no probe)
Fnirsi-138 Pro
No battery, no probe $17
Battery no probe was $19
Probe, no battery was $21
FNIRSI-138 Pro I paid $23 with battery, probe.

NOTE: There's a warning not to touch metal with connecting the scope to higher voltage sources.

My experience = Battery time: 4 - 5 hours. Recharge: less than 2 hours
===============================
Paraphrased from their manual: FNIRSI-138PRO is a handheld oscilloscope for people in maintenance, R&D, and education. It has a real-time sampling rate of 2.5MS/sand a 200KHz bandwidth. With full trigger function (single, normal, automatic).
It has a one-button AUTO feature.The display has a resolution of 320*240. Optional built-in 1250 mAh lithium battery with continuous use of about 4 hours.
PRODUCT PARAMETERS
USB C supply voltage: 5-6V
Type-C Lithium battery: 4-9V Capacity / 1250mA/h
Sampling Rate: 2.5MS/s
Bandwidth: 200 kHz
Voltage range: X1:±40V(Vpp:80V) X10:±400V(Vpp:800V)
Trigger method: AUTO/Normal/Single
Coupling: AC/DC
PWM output: 3.3V, Frequency:0~80kHz, Duty cycle:0~100%
Display: 2.4" 320*240Size: 65*60*18mm
Weight: 53g (Without battery) 72g (With battery)

===============================
DSO138 Videos

[tenlittleindians]

I wish I had an internal battery in my tiny version.

Your oscilloscope on the right tempted me forever on Banggood until they offered a kit scope about the size of your new one for similar money.

I bought the kit and soldered it together a few years ago and really liked it for being so compact. However mine also has the power jack which ties me either to a wall outlet or to an external battery.

Mine does have a nice case which sold me over your "red" scope kit at the time.

I also bought a cheap component analyzer a few years ago without a case and printed a case for it.

The device I wish I had instead of my oscilloscope and part checker is one of those compact devices with the oscilloscope and parts checker and a frequency generator all in one!

They are compact and preassembled but I can't justify buying something I really don't need. If they ever put them on sale for a ridiculous cheap price I'm afraid to admit I'll pull the trigger and buy one anyway.

If your like the rest of us you must have wondered how are we ever going to keep all these things charged!

It's like having 15 wind-up clocks in the house and your always finding one that got missed during the last inspection.

[nello]

to select 10x you press change until curser is on volts then press and hold OK until it changes.

[pasanlaksitha]

can i messure milliamps from this osiloscope. I'm doing energy efficient some of my circuit projects so i need to messure how much current flow in my circuits

[retread]

How would you monitor a 240V AC power supply

[td]

Thought this video might be of interest to TS: Oscillator Sniffer | Close Proximity AM Transmitter | Ferrite Antenna Booster/YT/RestoreOld Radios Channel.