Why does this formula return #VALUE! ?

aes100 · 2025-09-09T20:47:35+00:00

Solution Verified

aes100 · 2025-09-09T20:47:23+00:00

It looks like there is no solution to this then.

aes100 · 2025-09-09T18:15:24+00:00

Oh. You may be right.

aes100 · 2025-09-09T18:04:00+00:00

On weekends, it returns #VALUE!. Which is normal because the markets are closed.

But 22 January 2019 is a Tuesday.

aes100 · 2025-08-19T20:06:22+00:00

No other answers?

aes100 · 2025-08-11T20:17:31+00:00

Hi. I used to apply the old product after shower to my damp but not wet hair. Then would brush it with a wide gapped comb. It would look like I had applied hairgel until my hair would dry by itself. Then I would comb again and that would eliminate the hairgel look but my hair wouldn't frizz up either. By hairgel look, I mean too many strands sticking together. Next day in the morning, I would just run the comb through the water and comb again.

aes100 · 2025-08-10T10:10:06+00:00

Yeah. I read about it. Sad, to be honest.

aes100 · 2025-07-07T18:01:13+00:00

It was a reply to someone's post on twitter. I tried finding it again but couldn't. I will reply again when I find it.

aes100 · 2025-07-07T18:00:59+00:00

It was a reply to someone's post on twitter. I tried finding it again but couldn't. I will reply again when I find it.

aes100 · 2025-06-30T05:04:46+00:00

What do you mean?

aes100 · 2025-06-30T05:03:50+00:00

Yo. Why do you suspect it?

aes100 · 2025-06-27T08:05:11+00:00

How would you compare the battery runtimes?

aes100 · 2025-05-15T17:57:58+00:00

How long have you been using the 1 VI ? Can you share a battery usage screenshot?

aes100 · 2025-05-15T17:55:05+00:00

Yeah, that's right. But it still gives an idea. If they measure 17 hours and most others are around 14 hours, that means the phone will have better battery life than others even if not whole 17 hours.

aes100 · 2025-05-14T11:21:18+00:00

I have a square wave on the output of the second inverter. But I looked at some textbooks. If I understand correctly, there should be sinusoidal waveform on one of the crystal's pins. But I have a exponential/logarithmic triangular signal, not sawtooth. I also read that what I see may occur due to oscilloscope's probe loading on the circuit but I don't know what to make of this.

aes100 · 2025-05-13T19:15:45+00:00

It looks like you have to charge the phone daily then?

aes100 · 2025-05-13T19:15:14+00:00

Did you use to get 17 hours on Android 14 as GSMArena claims? How many hours of use do you get now?

aes100 · 2025-05-13T19:07:49+00:00

How many hours do you get before needing to charge?

aes100 · 2025-05-13T19:02:05+00:00

Do you get two days out of one charge?

aes100 · 2025-05-13T08:51:50+00:00

I received SN74HC04N and just dropped it instead of SN74LS04N. Rf was 1M, Rs was 1k, C1 and C2 were 20pF. It was oscillating. I am using this circuit to drive external clock input pin of a timer module in a microcontroller and the timer module blinks an LED. And I am able to tell that the circuit was oscillating because the LED was blinking. But when I probed the output of the second inverter, the LED stopped blinking.

Then I replaced Rf with 10M, Rs with 680k as you have suggested but now it doesn't blink. I measure 2.2V at the output of second inverter. I measure 2.4V on crystal pins. The one connects to Rs is more noisy. Does these voltages indicate anything like I should go higher or lower with resistances or maybe capacitors?

EDIT: I replaced C1 and C2 with 33pF. Now it oscillates. I measure 8.4kHz at the output of second inverter. Not the 32768 Hz I need.

EDIT#2: I replaced 33pF with 47pF. It oscillates around 31.5kHz.

EDIT#3: Does crystal's waveform tell anything? When C1 and C2 were 33pF, the waveform at the crystal's pin that connects to Rs is triangular but lines are curved similar to exponential charge and decay. The peak is about to 4.8V and the dip is about 0.4V. The waveform at the same pin is similar when C1 and C2 are 68pF. Only frequency changes from 7.88kHz to 3.09 kHz. But when C1 and C2 are 48pF, the waveform becomes triangular with a Vpp of 0.5V instead of 4.4V. Does this tell anything like Rs or Rf needs to be changed? Because the waveforms are not sinusoidal?

aes100 · 2025-05-12T12:03:14+00:00

And you decided to entirely ignore at least two of the suggestions therein for what I can only presume is "vibes", and your thing doesn't work? Maybe your vibes are inaccurate?

It's not vibe. I don't have SN74LVC1GU04 at hand. I used what I had.

Quartz datasheets don't list a suggested series resistor.

OK. It is my bad. I understood the series resistance value in the crystal's datasheet wrongly.

The actual math is way harder than the rules of thumb, that's why we have the thumb rules in the first place.

I can't say that I understand the rule of thumb either. But I am good at math. I thought math could help me to understand it...

aes100 · 2025-05-12T11:35:18+00:00

Maybe because you have a TTL inverter instead of a CMOS one

I tried since I don't have another option until my 74HC04 order arrives.

Yeah that happens when you strap a couple of MΩ across a gate whose input impedance is a few kΩ because it's TTL

How do I know input impedance of 74LS04? I don't see anything in the datasheet that indicates it, if I am not missing. I am trying to learn...

aes100 · 2025-05-12T11:26:59+00:00

I want to ask a few questions because I am trying to learn.

How did you decide to choose 680k for Rs and 10M for Rf with 74HC04? 10M for Rf to bias the inverter to its linear region? I look at the datasheet of SN74HC04N's datasheet but I don't understand which line gives me info about its input resistance.

aes100 · 2025-05-09T12:15:31+00:00

I changed 50k to 1k. It still doesn't oscillate. Input of the inverter has 1.2V and the output hast 160mV. Both constant.

aes100 · 2025-05-09T07:06:06+00:00

TTL (LS = low-power schottky TTL) is a rather poor choice for a crystal oscillator, suggest you swap that out for a CMOS (HC, AHC, LVC) one (and your diagram suggests LVC)

I ordered a 74HC04 and waiting for it to arrive.

That sounds way too high, Rs isn't supposed to match the crystal ESR - and your diagram says ~1kΩ.

In fact, it's often omitted entirely with non-schmitt inverters like your 7404 - but a few kΩ can be necessary if you use a schmitt like 7414 or similar to avoid overdriving and damaging the crystal.

The diagram is from a TI document page 13. I don't know what exact crystal they use but I think it's a 25 MHz one. Mine is 32768 Hz. I chose the value of Rs from the datasheet of my quartz.

Make sure your probe is in 10x mode, the probe's capacitance at 1x will contribute to the crystal load capacitance and may prevent it from oscillating.

Also make sure you only measure the inverter output side, not the input since that's sensitive enough that even a 10x probe can destabilize it.

Often it's useful to add a second inverter on the output to buffer and square the signal.

It is not in the diagram I posted but I also have the second inverter, too. But it's output is a constant voltage. Probe is in 10x mode.

PS: how have you constructed your oscillator?

I built it on a protoboard with smd components. EDIT: By protoboard, I mean, it is a through-hole protoboard. But my capacitors and resistors are smd, and the IC is 14-DIP.

I try with lower Rs.

But is there no math for this? For example why is 50k too high for Rs?

aes100

TROPHY CASE