Help needed with triangle wave circuit / Op amp mosfet driver.

AnalogKid

Joined Aug 1, 2013
8,306
Here is an alternate version of your circuit, based on two CMOS 555's. These will turn on the FETs more crisply than a 2 K pull up resistor. U1 is a symmetrical squarewave oscillator, and U2 is acting as an inverting power driver. C2 and C3 are the 555 decoupling caps; they are shown attached to the Reset input for drawing convenience. NF should be nF, but my software does only uppercase component values. The FETs do not have to be the part number on the drawing; they can be just about anything appropriate for the load.

Of course, U2 / Q2 / C3 are not needed if you are driving only one cell.

Because this circuit has only one timing resistor and capacitor, it is much easier to calculate and to make adjustable. The timing equation is in the LMC555 datasheet.

ak
Electrolysis-1-c.gif
 
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Danko

Joined Nov 22, 2017
870
NO ELECTROLYSIS...
1578584993556.png
Link 1
Link 2
EDIT:
Two metal plates in electrolyte are supercapacitor.
Every square centimeter of that capacitor has about 20μF capacitance.
= = = = = = = = = = = = = = = =
On simulation below V1 is 5V DC:

1578585636054.png
Compare green curves (H2+O2 output) in both simulations.
 

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DickCappels

Joined Aug 21, 2008
6,187
After messing around, iv decieded on a square wave design, which i did and scrapped because the triangle wave was slightly more effiecent,however at least i can drive another cell on the inverted side, obviously its going to produce a mixture of both o2 and H but it just for testing. But made it up , its only 20khz as my intrest was cavitation,but going to make it 25+khz like in the paper. Did some testing with tap water, saw some bubbles so i knew it was working. Then wanted to load test it so poured in aload of salt,which was a disaster and made a mess, shot up to 9 amps, still worked so i guess thats a bonus.View attachment 196195
A fellow I know used to manage a chlorine gas plant. He says the process as pretty simple: Just run current through saltwater.

Do not add salt (NaCl) unless you want to make chlorine gas.
 

Danko

Joined Nov 22, 2017
870
Do Not Use Baking Soda Period End Of Story!
Quote:
"... On electrolysis of NaHCO3, the Na+ ion will rush to the cathode and you will get:-
2Na+ + 2e- + 2H2O -----> 2NaOH + H2 and HCO3- + H2O -------> H2CO3 + OH-
Also
H2CO3 --------> H2O + CO2
Also
CO2 + 2H+ + 2e- -----> CO + H2O
Also
CO + 2H+ + 2e- ------> C + H2O
Conclusion: On adding NaHCO3 a whole range of chemical processes can take place but due to the nature of alkali metals, the one sure conclusion is that Hydroxides will be formed. DO NOT BE DECIVED into thinking that if you make a completely safe electrolytic solution using NaHCO3 or other carbonates that you end up with a completely safe electrolytic solution after use. If one takes pH readings of the electrolytic solution over time, one can access the progress of the carbonate solution (pH will increase with increasing Alkalinity), but my advice is play it safe, where PPE.
But when someone intentionally publishes that using baking soda is safe and does not put out carbon monoxide, sure, there is hydrogen, and sure, there is some CO2, but there is also enough CO to be lethal. ..."
 

Thread Starter

RIKRIK

Joined Oct 11, 2019
60
Thankyou danko, you are very knowledgeable on the topic and i really am greatfull for all your advice. Also dickC when i made the mistake of using salt water i was actualy concerned enouth the stop my experiment after a couple on minutes as the room smelt of a swimming pool and i had to open all my windows. Water turned yellow. Which did give me the idea of maybe it being usefull for drinking water treatment.
 

Thread Starter

RIKRIK

Joined Oct 11, 2019
60
well i did speak to a guy a while back who use to add a small about of plain beach to his rain water collection barrels for drinking water, however im not a chemist, so i wont be testing it :) i was thinking more third world applications. anyways another vid
, next test 3 cells in a tube, should come out to about 5a, still waiting on some safer electrolyte.
 

Danko

Joined Nov 22, 2017
870
danko, my question is it seems you use quite alot of electrolyte, iv seen others use 20% of the waters weight of koh
30% KOH solution has maximal conductivity and it is "standard" for industrial electrolyzers:
1579015576550.png
6.887 moles/liter = 386.4 grams/liter = 300 grams of KOH+700 grams of water = 30% solution.
for the price and the amount needed
Does not matter what is price of KOH, because one charge of electrolyte serves several years.
plus it being quite nasty stuff, its seems very counter intuitive for a green form of energy to use large amounts of corrosives. I am wondering if you have had success with lower quantities. My next design is listed below, its still mixed gas's but it gives me the opportunity to experiment more on a budget atm about £50. one down side is the amount of connections, but it means i can use thinner wire , also i imagine laying it out like in the picture, the positive is forced to flow to the negative. its going to slide into a clear perspex tube about 2mm larger than the plastic spacers. Also the crimp connectors arnt perfect as they will corrode but hay ho, thats what i get for dipping into the hobby fund by buying a few bags of specialty Ethiopian ground coffee. did i make the right choice, i think so...
About corrosion.
To eliminate corrosion, metal parts should be made all from low-carbon steel or all from stainless steel or all from nickel, only.
Instead crimp connectors and power wires should be used straps with holes on ends, made from metal of choice above.
Wires should be connected to ends of straps out of electrolyte.
EDIT:
KOH is "green" stuff
Quote:
"Due to its low salt index and high solubility, caustic potash also serves in the manufacture of liquid fertiliser mixtures.
KOH liquid is known to increase crop yield and to improve the drought tolerance of crops.
"
 
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Thread Starter

RIKRIK

Joined Oct 11, 2019
60
AnalogKid took your advice :)

okay update :D , remodeled the cell, added washer spacers between the wire connector and plates, seems to have increased the amp draw (acting like a resistor?), while also increasing production between the plates. this video is straight cold tap water no pwm @ 5a,


i did do a 30khz test, but i wanted to test it with no pwm, to see if there was actually any visual difference in amps and production , this resulted in me accidentally short circuiting my board. so instead of rebuilding the original circuit, i am using a 555 to replicate the experiment as it gives me more choice but will do the same as the other circuit.

now the differences / visual observation which i feel should be looked at further, however these could be failures with my circuit / equipment. as im not 100% sure it was the short circuit.
no pwm 5a / pwm 4a
no pwm - meter goes from 4.5a to 5a in about a second after turn on / pwm - meter goes up in incremental steps (1,1.5,2,2.5) up to 4a over about 4 seconds.
no pwm - when pulled out of water amps drop to zero / pwm - when lifted out of water, drops to 2a , but continues to make bubbling sound for afew seconds, before tapering off.

now the painfully idiotic bit for me, i didnt record it , because i wanted to see if i got the same from no pwm first. but new circuit.
555.png

.
 

ci139

Joined Jul 11, 2016
1,187
you likely should somehow measure the volume and content of that output . . .
the setup could be 2 connected canisters
the one with the eletrolyzer sealed and filled to top -- so if the gas forms it pusher some electrolyte out of the tank and that gives you ? the volume under some pressure

i'm a bad weather bird here - years ago i did statistics over my Joule Thief variants that looked bright but were not that good as they looked by their current output . . . and were even poorer by their efficiency - though there were some exceptions . . . is when i started to use the LTSpice -- to work out what i was thinking wrong . . . but the Spice also has some 10% trustiness - but with experience you can tell when and how to hit that 10% more frequently ...
 

Thread Starter

RIKRIK

Joined Oct 11, 2019
60
KOH is "green" stuff
Quote:
"Due to its low salt index and high solubility, caustic potash also serves in the manufacture of liquid fertiliser mixtures.
KOH liquid is known to increase crop yield and to improve the drought tolerance of crops.
"

good to know danko. however my plants are rather drought tolerant :)
IMG_20191109_010650180.jpgIMG_20191109_010957723.jpg

ci139
im currently building a air tight tube, with a hose in so i can measure liters per minute. well its very early days, new circuit, do actually want to make a separate hydrogen and oxygen generator, but its been interesting enough for me to continue with the mixed gas. theres so much stuff on youtube about hho which is miss information, lucky for me, danko, has gave me some basics. getting into some what a fringe area, il see where it leads.

Joule Thief , you get any interesting results. any weirdness.
 

Danko

Joined Nov 22, 2017
870
I finished comparative test between DC and 30kHz powered cell.
With mean current 50 mA, voltage on cell and time required
for generating 5.5 ml gaseous mix, measured.
----------------------------
Results:
Time (DC) = 335 s.
Voltage (DC) = 3.16 V.
Time (30 kHz) = 344 s.
Voltage (30 kHz) = 3.48 V.
-----------------------------
So, energy (DC) = 0.05 A * 3.16 V * 335 s = 52.93 W*s,
energy (30 kHz) = 0.05 A * 3.48 V * 344 s = 59.86 W*s.
-----------------------------
Dynamic resistance of cell can be calculated,
using Vtop and Vbase values (see oscillogram).
Then R_dyn_cell = (V_top - V_base) / I_pulse =
= (3.48 V - 2.78 V) / 0.1 A = 7 Ω.
=================
For decreasing capacitance of electrical double layer,
electrodes of electrolyzer made from thin steel nails
1.5 mm dia, length exposed to electrolyte - 22 mm.
Distance between axes of electrodes is 7.5 mm.
Surface area of each electrode is 1 sq. centimeter.
Electrolyte - saturated solution of sodium bicarbonate.

1579519165226.pngCell_1.jpg Cell_2.jpg
1579544643520.png 1579544432188.png
 
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ci139

Joined Jul 11, 2016
1,187
electrolyser made from thin steel nails 1.5 mm dia, length exposed to electrolyte - 22 mm.
(-1-) is it matrix or two nails only ?

// (-2-) \( S=S_B+S_S=\pi·R^2+2·\pi·R·H=\pi·D·\left({\frac{D}4+H}\right)≈105.44mm^2=1.0544cm^2 =1cm^2·\left({100\%+5.44\%}\right) \) -- if the tip is conic or faceted you may be more correct (but your description does not specify any) + i got 1.6mm ones with m≈2 ... 2.5mm assuming m=2.25mm , using the cone formula:
\( S=S_C+S_S=\pi·R·m+2·\pi·R·\left({H-\sqrt{m^2-R^2}}\right)≈98.9775mm^2=0.989775cm^2 =1cm^2·\left({100\%-1.0225\%}\right) \)
 
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Danko

Joined Nov 22, 2017
870
(-1-) is it matrix or two nails only ?
S=SB+SS=π⋅R2+2⋅π⋅R⋅H=π⋅D⋅(D4+H)≈105.44mm2=1.0544cm2=1cm2⋅(100%+5.44%)S=SB+SS=π·R2+2·π·R·H=π·D·(D4+H)≈105.44mm2=1.0544cm2=1cm2·(100%+5.44%) S=S_B+S_S=\pi·R^2+2·\pi·R·H=\pi·D·\left({\frac{D}4+H}\right)≈105.44mm^2=1.0544cm^2 =1cm^2·\left({100\%+5.44\%}\right)
Is all good with you?
I did not say 1.0000 sq. cm.
I said 1 sq. cm.
Do you feel difference?
 

ci139

Joined Jul 11, 2016
1,187
you didn't answer the 1 question . . . the output may also depend on the "shape" of the electrolyzer . . . and electrode distances
. . . also how you get the RMS pulsed voltage and current -- i mean "you" need to measrue them "on the electrolyzer terminals" (it's quoted because the setup may be more complicated than that → the meters reponse times , accumulating systematic errors . . .)

-- the second (also by the priority , plus - set as a comment by // ) - i just were thinking online
 
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Thread Starter

RIKRIK

Joined Oct 11, 2019
60
Alot of maths there people, thank for participating in the experiments , CELL done, at the moment is not great 6 cells, draws about 15a no pwm, just tap water, no added electrolyte, currently waiting on a 555 timer to finish my circuit, to try it with 30khz and cross my fingers for more production, reduced wattage.
 

ci139

Joined Jul 11, 2016
1,187
it's the type of **** where all the tiny nuances may dial in
why i think so . . . if it's the "resonance based" then the resonance limits are . . . narrow
. . .
to be able to meet those boundaries the very physical design (also dynamic gass + molecular flows , electrode orientation and shape) may need to be with counted (and there's no much information about)
. . . it is a head ace

it may be suspected that the energy conservation in this process addresses to mechanical https://en.wikipedia.org/wiki/Impulse_(physics) of molecular transport - so if you kick it a go in one direction it continues from (mechanical + electrical -- fluid's charge field in the electrolytic capacitor) inertia ... while when under a constant force some power goes "smoking into the air"

also the continuos energy to molecules may increase bounces (energy loss) in "not preferred directions"
 
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Danko

Joined Nov 22, 2017
870
Basically i am trying to replica a wave form from a research study paper. However the guy doing the study had a large waveform generator, hooked up to the mains , in which he tested 3 waveforms, square, triangle and sine, and came to the conclusion that a triangewave at 25/30khz yielded the best results. heres the paper https://drive.google.com/open?id=1H-N0w95-LL5lIIu_JSMPD8k4WF_NURfW
Most of "researchers" in Pulsed DC Water Electrolysis are swindlers.
They use that topic for grants obtainment.
Why not read honest research papers?

For example:

1. "Water Electrolysis and Pulsed Direct Current"
Aly H. Shaaban
Applied Research Associates Incorporated, Tyndall Air Force Base, Florida 32403-0128

2. "Analysis of the Frequency Response of a Water Electrolysis cell"
Kaveh Mazloomi* , Nasri Sulaiman, Siti Anom Ahmad, Nurul Amziah Md. Yunus
Department of Electrical and Electronic Engineering, Faculty of Engineering, University Putra Malaysia.
 

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