DT-2234C+ Digital Tachometer Teardown and Review

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Күн бұрын

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@jaakkooksa5374 6 жыл бұрын

I bought one from Aliexpress for 7 or 8 euros incl. shipping and tested with a lab power supply and a computer fan. It appears to work accurately because the measured RPM is consistent and roughly matches the values given in the fan's data sheet. Note, 9V battery not included, prepare to expend 2 extra euros for a battery :-) I intend to use this device for the H adjustment in chainsaw carburetors where going to too high an RPM can case the engine to seize.

@FreedomAddicted 2 жыл бұрын

Thank you for the vid. Very professional review. Nice test.

@felixf5211 3 жыл бұрын

A tip: If your tape is on a reflective surface, the tach won't read accurately aimed straight at the tape, like on a polished chuck as an example. However, if you place the tach on a 45* angle below the object with the tape, it will read accurately.

@attic636 2 жыл бұрын

Good idea. But how would ylou measure speed of a record player? Mine has got a turning plate which is polished and reflective from side-view (surely the best position for measuring). And I cannot check its speed from below. All I know is that records are playing a little too fast while listening, after I had replaced the old 12 V (80 mA) power supply with a broken cable for a new one that has got 12 V 400 mA. I know how to reduce voltage with a step-down converter, but I want to have confirmed correct speed values od 33 rpm and 45 rpm when I try to set a new matching voltage.

@CookieTube Жыл бұрын

@@attic636 You DO NOT measure the speed of a record player with such tachometers! That is like using a sledgehammer to fasten a stapel. The accuracy of such meters is not great in practice! Do not be fooled by the test he did with the PWM pulsing LED. That is not how you measure in practice. In practice you will never get that accurate reflections from light. If you want an accurate record player, you use those (usually paper) discs they sell with a black/white pattern on them. You put them on your record player while it is spinning. And if you notice the pattern being still (no rotational movement) you have the correct speed. If they slightly move CW or CCW, your speed is a bit too fast or slow. They should cost 10 times less than the cheapest tachometer you can find and they are 10000000 times more accurate to the point of being perfection (depends on how exact they have been made). In fact, expensive record players have them build in on the side of the spinning plateau with a tiny light on them so you can clearly see if they are spinning absolutely correct or not. *Search for **_"vinyl stroboscope disc"_** or **_"turntable speed calibration mat"_** .* Shouldn't cost more than $5-$10. Also, there is no practical difference at all where you measure the rotation (since you said: _"surely the best position for measuring"_ ). The whole point of these tachometers is that they literally only measure the amount of reflected light pulses pulses. So, where you measure it does not matter at all! It can be from almost the center of a disc, from almost the outer diameter, from the side, underneath, on top, ... makes no difference at all in terms of accuracy. It is all literally the same: amount of light pulses which pass by in a given amount of time; 1 rotation is 1 reflected pulse..... NOT to be confused with linear or tangential speed (in which case it absolutely matters)! Also, if the thing you want to measure is reflective, then put some black non reflective tape on it, instead of a reflective tape. These tachometers measure pulses of light, or better said: the difference in light on the light detecting diode, or not. They usually measure on the leading edge of the reflective curve. Hence why it also doesn't matter how wide your 'reflective tape' is... as long as there is a sudden difference/drop in reflection, they should be able to measure it.

@CookieTube Жыл бұрын

@@attic636 No, no need for an optical tachometer tool, nor for a stroboscope. You just need to put a proper AC mains operated incandescent or fluorescent (but non CFL) light bulb close to it. And look at the 'apparent' movement of the stripes with just only your eyes. You are indeed looking for the 'standing still' effect. In this case, the accuracy of the disc and using your eyes would be orders of magnitude higher than using an optical tachometer like the one shown in the video (make sure you aren't drunk though... or it might not work). So, as for the need of a stroboscope to make the effect appear: you already have it: it is the AC mains electricity from your own power grid! *That* is why the discs are calibrated to 50Hz and/or 60Hz and not some other, but totally possible, frequency. There is no electronical secret or audiophile 'magic' involved in those numbers other than pure old plain convenience. You can in fact design and create a disc calibrated to whatever frequency you fancy, and it will work with an appropriate strobe light. But why bother when people already have 50Hz or 60Hz at their disposal in their own house which has always been flickering lamps since the beginning of the invention of electrical lighting (you may have simply never noticed it though --- btw, in that case: lucky you, because some people are subconsciously sensitive to it and get headaches because of it after a while).... Thus, there is no special relation between how your turntable operates and this specific frequency in context of the function of that disc. Well accept of course, the turntable indeed needs to be compatible with your power grid too or it will blow up. lol. But how it uses that: to drive a motor directly, or convert it to DC first and drive the motors that way, or whatever else.... has nothing to do with how such a disc operates. It is just pure convenience that the power grid can do double duty as both to power the turntable in whatever direct or indirect way, and can also be used as a way to create a strobing light (especially in the old days) using plain old household lamps in case your turntable didn't have such calibrations stripes build-in on the side of its platter . So, all you need is an AC mains powered normal old style *filament/incandescent lamp* , or a *long-tube fluorescent lamp* . It wont work with those fancy energy saving CFL types though, as they don't flicker at the rate of your AC mains. Also modern complete LED fixtures wont work because they all use rectifiers and capacitors, or even dimmable drivers (unless you make one yourself specifically for this purpose which is directly connected to the mains with only the appropriate resistors so you don't blow up the led and nothing else. Or if you use a PWM-driver. In that case it would even be far better than anything else because a led will turn on/off instantly, opposed to any other type of lamp which always has a small gradient in their on/off cycle) But in case you don't find a suitable light in your home anymore: yeah, then you do need a 'special' dedicated stroboscope. But the only way they are 'special' is that they flicker at 50Hz or 60Hz though. They are absolutely nothing more than a simple incandescent or fluorescent lamp you plug into the mains, which you can buy yourself in any DIY store......(well, at least I hope you can still buy them...lol). Or there are also battery operated lights for this use specifically, or via a power adapter like the listing you found on eBay. They all simply use just a small PWM-generator to flicker a led at 50 or 60Hz. Note: that eBay listing you pointed at is indeed for such a 'special' strobe light, but it also has the stroboscopic disc included (so you don't need to buy both separately). But note that that specific light is not battery operated though, it needs a power adapter (12V, which should also be included in that package. 110V/12V on that eBay listing I believe). This is the exact same package as you can find on hundreds of websites. And if you search at the source (China/ AliExpress), you'll find the exact same bundle for around $30 (including the choice of 12V adapter for 110V or 220V). Search for "stroboscopic turntable light" on AliExpress.

@whatworkedforme Жыл бұрын

you went to great lengths to rubbish this YT video content..@@CookieTube I found it useful.. and no this particular Tachometer is not about 10 times the price.. it is at the lower of the price of your piece of paper (and as you state if you get one made accurately - how would the user know). I'm not rubbishing your advice either; each to his own but it is fine for a lot of applications; esp the ones I foresee using it on and glad I saw it tested. I don't think this tool is intended to be laboratory standard either.. esp for the price (currently £6 UK on Aliexpress.

@atomicskull6405 5 жыл бұрын

I just got one of these from Ebay and they have revised the design at some point. The switches are now properly soldered from the back and the laser diode is much smaller, about the same size and shape as a ceramic disk capacitor and won't flap around. Though I still put a blob of electronics grade silicone on the back of the component to protect it from vibration while I had it open. Overall the internal build quality has been greatly improved.

@NearFarMedia 5 жыл бұрын

Nice, good to hear they made the improvements.

@ronz101 Жыл бұрын

Suggest that same rpm test on a lawnmower blade and see what happens. Should be between 1300/1500rpm as sweet spots.

@johnclegg6739 6 жыл бұрын

Wasn't soldered on the backside ? Doesn't matter as the hole through the pcb is metallised ( gold or other ) but thanks , have bought one and am going to link it up to a counter to make a Speedometer/Revcounter test bed...John

@74LS324 2 жыл бұрын

I have one, used once, stored for 4 months, and when the battery is connected it won't turn on...

@shagarcool 2 жыл бұрын

I've only used it once and then the display is displaying incorrectly

@cmguitar50 3 жыл бұрын

Hey! Thanks for the review! I have one of theses and it suddenly stopped working. R11 looks toasted - totally white. what's the value for R11? Thanks.

@NearFarMedia 3 жыл бұрын

In my unit, that resistor appears to be an 0805 size with marking '152' which is a 1.5 Kilo Ohm resistor.

@cmguitar50 3 жыл бұрын

@@NearFarMedia Thanks - Testing the meter is on my bucket list

@devilishgaming1469 8 ай бұрын

The inside of mine does not look like that and I bought the same model

@funkynerd_com 2 жыл бұрын

Just bought one off Amazon.....then decided to look for reviews. phew. Sigh of relief that it's not junk.

@behramcooper3691 2 жыл бұрын

How about a demo with a fan instead of just an LED?

@countinhosuarez8891 2 жыл бұрын

Great video Sir !!! , just an inquiry, what time of battery do we use for this digital Tachometer ?, I am currently planing to buy one

@attic636 2 жыл бұрын

Can you tell how to delete all RPM values from its memory? When pressing the mem-button it can be quite confusing to tell whether a value shown on display is one from the running test or from an earlier speed test days ago.

@joao.mambelli 2 жыл бұрын

it stores 3 values after you measure: highest (preceded by a "up"), lowest (preceded by a "dn". this value is retrieved always after a highest value is reached) and the last value registered when you stop measuring (preceded by a "la"). if you hold the mem button, it will show, for example, the highest value. if you release the mem button and hold it again, them it will show the lowest value, and so on... values from previous measurements are always overwritten by the last measurement

@attic636 2 жыл бұрын

@@joao.mambelli Thanks for telling me. 😄 Basically, the manual should explain that.

@josephcaruana9165 4 жыл бұрын

Kindly do you know how to reset the memory and what is the function of the MEM?

@granttiddy7414 3 жыл бұрын

MEM displays Maximum reading (up), Minimum reading (dn), Last reading (la) - it resets automatically each time you do a new TEST

@kaja332 5 ай бұрын

Koja je baterija

@levoochka 5 жыл бұрын

can you check RPM's on a chain saw with this tachometer?

@NearFarMedia 5 жыл бұрын

If you are able to safely access the chain sprocket while the chainsaw is running you probably could I think.

@sureshlingabathina 4 жыл бұрын

Good test

@alexandruaneste8723 6 жыл бұрын

I watched the video and bought one. I guess if it would be working would be accurate but mine does not work at all

@NearFarMedia 6 жыл бұрын

It might be worth opening it up and poking any suspect solder joints with a soldering iron and checking that the laser and sensor are aligned properly.