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Complete Your Profile- andrewty commented on Steve Willson Kujur's instructable How to Make an Automatic 12V Battery Charger6 months ago
- andrewty commented on rmomberg's instructable Lab ATX Powersupply9 months ago
This instructable is much better than the usual rubbish we get here.Well done.I did not know the 10W rule !I'll have to keep that >=2A loading in mind.
View Instructable »Is there any chance you can edit out your spelling errors?
- andrewty commented on Xexos's instructable Kitchen Knife Saya9 months agoView Instructable »
Be careful with UK knife law.One must have good reason to have a knife in a place to which the public have access.There are a few exceptions:eg, a folding type penknife with a blade less than 75mm long and the blade does not lock open.
- andrewty commented on lonesoulsurfer's instructable Portable Analogue Power Supply 10 months agoView Instructable »
You were doing just fine until you replied with this. Now I am gone. Don't ask for help with that attitude.
- andrewty commented on seamster's instructable Speed-Tuning Spinner Bearings10 months agoView Instructable »
Ball and roller bearings are made in different "speed" grades.The lowest speed are the tightest, with a tiny diametrical clearance.The highest speed have the largest diametrical clearance.One can check the clearance by trying to rock the innner against the outer. A slow version will have very little sideways rocking. After cleaning this will be more easily detectable.Cheap bearings will probably have such wide tolerances that testing a group of cleaned versions will give a very wide range of apparent rocking/slackness. some due to balls of different diameters, some due to out of round of thei nner and/or outer and some due to different diametrical clearance.
- andrewty commented on Tool Using Animal's instructable Red Oak Pyramid Bow11 months agoView Instructable »
UK builders:It is illegal to hunt wirh a bow anywhere in the UK.Not birds, not animals, not fish. Nothing can be hunted with an arrow.Crossbows are illegal for hunting.Target points are OK for target shooting.As far as I know all other points are illegal.
- andrewty commented on Paige Russell's instructable 5 Ways to Make Hanging Lamps11 months agoView Instructable »
Where are the instructions for fusing?
- andrewty commented on Patel Darshil's instructable DIY Bench Power Supply for Hobbyists11 months ago
"This is the step down transformer which converts 230v into 12v and 24v DC as per need."No !A transformer changes the voltage of AC.It converts 230Vac to 12Vac and 24Vac. It does not change to 12v and 24v DC as per need !!!!!!
Useless.Where is the schematic to show how to convert low voltage AC to DC?Where is the schematic to show how to adjust the rectified and smoothed DC to a lower voltage?
View Instructable »"Use the step down transformer to convert 230v AC into 9v DC."How? Where are the construction details?"Use 10k Trimpot for Variable supply!!"Where are the construction details?
- andrewty commented on SimonLithedreamer's instructable Power Inductor Measurement Without LRC Meter11 months ago
very approximate.Your answer depneds on the difference between two very similar valuesThe inductive impedance is too low for this method to work.You need to use a much higher frequency and/or a much higher inductance.I suggest the voltage loss across the inductor be smilar to the voltage loss across the reference resistor.That would give you some chance of being nearly accurate to two significant figures.As is, your inductor measured value is not even accurate to 1 significant figure.
Very approximate.Your answer depends on the difference between two very similar valuesThe inductive impedance is too low for this method to work well.You need to use a much higher frequency and/or a much higher inductance.I suggest the voltage loss across the inductor be similar to the voltage loss across the reference resistor.That would give you some chance of being nearly accurate to two significant figures.As is, your inductor measured value is not even accurate to 1 significant figure.
View Instructable »his arithmetic is riddled with mistakes. Can't you see that?
- andrewty commented on mecanicafina's instructable Safe Capacitor Discharge Tool1 year agoView Instructable »
I use a pair of croc clips on leads with a 2k2 resistor soldered in circuit.The 2k2 limits the current of a 63V fully charged capacitor to <=29mApkA 2W resistor will initially get very warm if trying to discharge a 15mF cap from 63Vdc but it does cool down quite quickly as the charge dissipates. The 2k2 on a 15mF will be down to <5% of starting voltage in ~160seconds.
- andrewty commented on ajoyraman's instructable Extend Defective Fluorescent Tube-Light Life1 year ago
Instructables is about learning how to do "stuff".it's the learning that is important.
View Instructable »I am completely out of theloop and very definitely grey haired.
- andrewty followed Rock-n H Woodshop1 year ago
- andrewty completed the lesson Mitres in the class Table Saw Class1 year ago
- andrewty completed the lessons Tools + Materials, Ripping Wood and Meet Your Saw in the class Table Saw Class1 year ago
- andrewty enrolled in Table Saw Class1 year ago
- andrewty commented on TjB29's instructable How to Sharpen Used and Dull Drill Bits (By Hand!!)1 year agoView Instructable »
I do the opposite when rolling twisting the bit.I offer up the cutting lip to the stone and try to get the correct angle. You said 60degrees, that's close enough, but 56° to 59° is probably better. This gets closer to the preferred 114° to 118° tip.Once I have the drill bit at the correct angle to the face of the stone. I rotate the bit until the cutting lip to be sharpened is horizontal. The drill is now at right angles to the stone face, the lip is horizontal and the bit axis is at ~ 60°.Now gently push in holding those three angles accurately, the horizontal and the 60° to start grinding the cutting lip. Now I start to tilt the bit down at the blunt end and at the same time rotate the bit clockwise so that the lip comes up and away from the stone. The area beh...
see more » - andrewty commented on gomer394's instructable Home-made Anvil1 year ago
The blacksmith I worked with before I left school 49years ago told me that the anvil sits on a log that is 6feet below floor level. A log about about 7.5feet long gets the anvil to a nice working height.It's the springiness of the log down/along the grain that gives the anvil it's rebound ability.
The balcksmith I worked with before I left school 47years ago told me that the anvil sits on a log that is 6feet below floor level. A log about bout 7.5feet long gets the anvil to a nice working height.It's the springiness of the log down the grain that gives the anvil it's rebound ability.
View Instructable »The balcksmith I worked with before I left school 49years ago told me that the anvil sits on a log that is 6feet below floor level. A log about bout 7.5feet long gets the anvil to a nice working height.It's the springiness of the log down the grain that gives the anvil it's rebound ability.
- andrewty commented on Khaleel123's instructable 3D Printed Arduino OLED Watt Meter1 year ago
You could do with changing the title to include "DC Watt meter"You would need a multiplying function to calculate instantaneous I * V to generate a watt value.You can't just measure Irms and Vrms and just multiply. That excludes the load phase.Take a capacitor across the AC voltage. It absorbs virtually zero power even though the current is measured as significant mAac, or Aac.Same for an inductor. The reactive element of the load does not absorb power. Only the resistive part of the load absorbs power.
View Instructable »you could do with changing the title to include "DC Watt meter"You would need a multiplying function to calcukate instantaneous I * V to generate a watt value.You can't just measure Irms and Vrms and just multiply. That excludes the load phase.Take a capacitor across the AC voltage. It absorbs virtually zero power even though the current is measured as significant mAac or Aac.
- andrewty commented on Akshay Jha's instructable HI-FI 4 Channel Audio Amplifier VERY Simple and CHEAP!!!! 1 year agoView Instructable »
Have a look at the chip dissipation when delivering power to the 4ohms loads.The graph shows ~23W being dissipated when 1W is being delivered.the heatsink will need to be very large to get rid of 23W if you plan to have continuous average outputs of 1W into your loads.Look at the THD vs output graph.the signal distortion rises rapidly as the output passes above 15W It passes 0.1% THD when the output reaches ~18W into 4ohms when the supply has sagged to 14.4Vdc.The Absolute maximum operating voltage is specified as 18Vdc. Allowing for voltage sag at the supply pins makes this a quad 18W amplifier, not 40W.
- andrewty commented on 24Eng's instructable Power Drill to Belt Sander Conversion1 year agoView Instructable »
A next to useless instructible."you'll need a 3D printer," What !
- andrewty commented on tanner_tech's instructable Industrial Isolation Transformer From Trash1 year ago
the isolated supply feeds the Device Under Test (DUT).The isolated supply is NOT used to supply the grounded oscilloscope.Never probe anything with the scope probe deliberately ungrounded. or use the specialised differential probe that costs more than most scopes.
Using two identical mains transformers back to back gives an output voltage that equals the input, when there is no load current.As soon a load current is demanded, the output voltage drops.The voltage drop under full power load is roughly two times the voltage regulation of the mains transformer.eg, using two 230:55Vac 8% regulation 500VA mains transformers will give a 1:1 input to output voltage on any EU harmonised supply when no load current is drawn.When the 500W resistive load is applied, the voltage will drop to ~inputVac/(1+0.08)² ~86% input Vac. This resulting isolated voltage is well below the minimum voltage specified for an EU harmonised voltage.
View Instructable »I have to ask the same question.We have our newly boxed isolation transformer. It has a 3pin plug top ready to plug into the mains wall socket. It has a 3pin output socket. It has an MCB on the input and another MCB on the output.How do we wire up the Protective earths (PE)?Do we wire the enclosure to the PE?Do we wire the output socket to the PE?Do we fit a GFI (RCD, RCBO) to the input wiring?Do we fit a GFI to the output wiring?
- andrewty commented on Eric Brouwer's instructable Designing a Dual 40A PWM Speed Controller for Brushed Motors1 year agoView Instructable »
Are the gates to Q1 & Q3 (Pchannel mosFETS) drawn upside down?
- andrewty commented on iCoder's instructable How to Make a Command Prompt Defragmenter in Windows!! (works for All Versions of Windows)1 year agoView Instructable »
I try to download the 11steps, but the screen just refreshes and shows step 1 with the comments following on.I tried using the "view all steps" icon but it does the same taking me straight back to showing step 1.What's wrong?
- andrewty completed the lesson Class Overview in the class 3D Printing Class1 year ago
- andrewty enrolled in 3D Printing Class1 year ago
- andrewty commented on Sandeep_UNO's instructable How to Make Mini CNC 2D Plotter Using Scrap DVD Drive, L293d Motor Shield & Arduino1 year agoView Instructable »
where are the instructions.Many pics but no details to manufacture the mechanisms.Not much about how to control the electronics.
- andrewty commented on Yonatan24's instructable How to Remove a Stuck Nut (without stripping threading)1 year agoView Instructable »
WD40 is not a good lubricant for non rusty threads. WD40 is pretty poor as a penetrant.Use a penetrating lubricant formulated for that duty.many better suggestions in the earlier comments.
- andrewty commented on kitty 1234's instructable Control Your Home Appliances Using Arduino And Relay1 year ago
For, connecting the AC bulb to the relay properly:Connect live wire from AC wall outlet to Common port on relay and one terminal of AC bulb to Normally open terminal of Relay. Then, Connect the other terminal of AC bulb to GND on the AC wall outlet.NO !!!!connetc the other terminal of Mains bulb to NEUTRAL, not to GND.
View Instructable »For, connecting the AC bulb to the relay properly:Connect live wire from AC wall outlet to Common port on relay and one terminal of AC bulb to Normally open terminal of Relay. Then, Connect the other terminal of AC bulb to GND on the AC wall outlet.NO !!!!Connect the other terminal of Mains bulb to NEUTRAL, not to GND.
- andrewty commented on emills05's instructable How to Make a UTP Cable 1 year agoView Instructable »
the critical part is crimping the RJ onto the cable ends.But the pic is so bad that I can't see any detail !1 out 10
- andrewty commented on Victor805's instructable Drill press for ~$201 year agoView Instructable »
How good are the drawer slides at holding an accurate Up/Down motion?
- andrewty commented on mikeasaurus's instructable Corner Lamp1 year agoView Instructable »
Tungsten filament lamps run very hot.Fluorescents run a lot cooler.LED lamps are cooler still.Most can be touched without burning ones fingers.The exposed heatsink is usually the hottest part you can touch and it needs to be cooled to ensure a long life for the LEDs. They do not tolerate heat.A bit of air circulation helps, as does a big surface area to transfer heat to the surrounding air.
- andrewty commented on Josehf Murchison's instructable Salvaging Pure Silver BNC Connectors1 year agoView Instructable »
Is the black a corrsion product of the silver?How do you convert that back to silver?Other wise the silver gets thinner, until there is no silver left !
- andrewty commented on kidNeutrino's instructable Toughening a RFID Door Opener1 year agoView Instructable »
How you do send a signal to pull the door handle?
- andrewty commented on KeystoneScience's instructable Easy High Voltage Power Supply1 year agoView Instructable »
Could you explain the operation?
- andrewty commented on DerpyCyclops's instructable Easy Infrared Detector1 year agoView Instructable »
What is the other component on the plug in board?I can see the IR receiver at the top and the three lead out wires at the bottom.
- andrewty commented on MayukhN2's instructable H-Bridge for Dummies: How It Works and How to Make Your Own1 year agoView Instructable »
Could add some information on timing?How fast can they be switched with the controller?
- andrewty commented on Nematic!'s instructable Capacity Test of Fake 186501 year ago
Yes.You must take account of the voltage.Were the four batteries in series, or in parallel, or in a series parallel arrangement?Without this bit of information we cannot follow your analysis.
10400mAhr ?Why milli-amperes?It would be more comprehensible to state 10.4Ahr just like any other big battery.We are all used to evaluating the Ahr of car and leisure batteries. I recently bought a 22Ahr 3.7V lion battery pack.With that info I can see immediately that it is a big battery and what output voltage to expect. I can see that if I draw 1A it is likely to last ~22hours.
View Instructable »10400mAhr ?Why milli-amperes?It would be more comprehensible to state 10.4Ahr just like any other big battery.We are all used to evaluating the Ahr of car and leisure batteries. I recently bought a 22Ahr 3.7V lion battery pack.With that info I can see immediately that it is a big battery and what outpyt voltage to expect. I can see that if I draw 1A it is likely to last ~22hours.
- andrewty commented on geekrex's instructable How to make an Universal DC Motor Speed Controller1 year ago
if your motor is 5A thenthe mosFET must have a current rating exceeding 15A (3 times the normal maximum current)the irf530 has a max cold rating of only 14AThe 540 is much higher IdOr use a low Rds on type eg irlu8726 max I=80A and Rds on < 0.006ohms for best efficiency and cooler operation.
View Instructable »a ¼HP 12V motor will draw a lot of current. And even more when starting.Use a very high Id device with a very low Rds on.The example I gave above irlu8726 might do the job, or irfb3607 80A, 0.009ohmsAt 3 times the running current you will need a rating of >50A mosFET. 1HP=746W, ¼HP=186.5Wrunning current is ~186.5W/12V = 15.5A 3times that is ~47A ratingThe 555 timer will need a driver to charge up the gate capacitance. This becomes a much more onerous design.
- andrewty commented on HoracioP3's instructable LED bonding manually1 year agoView Instructable »
the Ultra violet is dangerous to eyes.Will this exposed LED emit enough UV to damage our eyes?
- andrewty commented on MakeStuff_MS's instructable DIY Homemade Constant 5V Voltage Source1 year ago
remove your instructible and read all the others.Try reading the datasheet.
I agree, this instructable is full of mistakes.The writer just does not understand how to get a 5V output.The LED could have been used as a minimum current load for the lm7805 series regulator. Some datasheets state that the minimum current should be 5mA and a few state 10mA minimum.Using a series resistor to limit the LED current is mandatory.For 5V out and 1.8Vf for the LED you need a resistor value of (5V-1.8V)/0.01mA = 320ohms, use a 330r for near 10mA min draw, or use 680r for 5mA min draw.If one decides they need reverse polarity protection then one can use the forward diode on the output. But we need to compensate for the forward voltage drop by adding a similar diode into the GND (labeled 2) of the regulator.The Vf (Vdrops) of the two diodes won't be identical, but close enough ...
see more »View Instructable »Agreed.This instructible is a complete waste of other Builders' time.It is a "how NOT to" ruin a useful idea.Read the lm7805 datasheet to see how to do it properly.
- andrewty commented on ThomasJ1's instructable Simple Vault Mechanism1 year agoView Instructable »
Please do a couple of instructables for telescope making.Can't get the reply to work so adding comment here instead.
- andrewty commented on Makin Sumthin From Nuthin's instructable Learn To Do Aluminum Sand Casting1 year agoView Instructable »
acetylene is too hot for melting aluminium.Propane is plenty hot enough.Oxygen is also too hot.A good propane/air burner will melt lead and aluminium.But probably not cast iron. That needs quite a bit more heat. Oxy/propane is probably OK for cast iron.
- andrewty commented on wobblycogs's instructable Converting a Quick Release Vice Into a Regular Vice1 year agoView Instructable »
We had quick releases on my school benches (4 off and over ten years as teacher). They never gave any trouble.I have one at home on my woodwork bench. It too has been totally reliable.Some manufacturer (not in the UK) must be making a codswallop of making bad clones.
nice instructable.Modern Lead Acid batteries do not suit >14V charging despite what some of the other comments say.The correct charging voltage for the modern chemistry in a Lead Acid battery is 13.8Vdc, unless the manufacturer tells you otherwise.The design uses a constant current pre-regulator.That acts as a short circuit protector. It does not need another protection device.Had this charger used a linear regulator, then it would become hot if short circuited and passing the set current into a near zero ohms load. But this charger is made up from pre-assembled switcher regulators. They do not overheat when taken to their maximum.I repeat, this battery charger is excellent and when used correctly will not damage modern Lead Acid batteries.Well done.