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Everything posted by HarryA
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I do not see your question; perhaps I am missing something
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Stepdown Transformer Turns Vs. Ampere
HarryA replied to electronics_shamim's topic in Electronics chit chat
If you are not big on building your own transformer look at: http://www.surplussales.com/homenew.html#Transformers example; 95VA Toroidal Transformer 117/234V to 2 x 15V or 30V at 3.2 Amps at 230 v that would give you say: 14.7 volts; a fat resistor would remove the 0.7 -
Stepdown Transformer Turns Vs. Ampere
HarryA replied to electronics_shamim's topic in Electronics chit chat
if: Vp = primary voltage, Ip =primary current, Np = number of primary windings. Vs = secondary voltage, Is = secondary current, Ns = number of secondary winding. then: Vp = Vs(Ns/Np) and Ip = Is(Ns/Np) example: To transform 120 vac to 12 vac, Vs = 120 vac (100/1000) = 12 vac Ns/Np = 0.1, say 100/1000 Using Ip = Is(Ns/Np) I am not clear which way you are going here. 0.3 amperes = 1 ampere (Ns/Np) Ns/Np = 0.3 say 180/600 or: 1 ampere = 0.3(Np/Ns) Np/Ns = 3.33.. or say 600/180 For power: Pp = Ps at 100% efficiency. Ps = n * Pp where n is the efficiency factor. n between 65 and 99 percent For 50 watts at the secondary and 75% efficiency the primary power would be: Pp watts= Ps/n = 50 vac/0.75 = 66.66... watts. For Impedance: Zp = Zs(Np/Ns)^2 To connect an 8 ohm speaker to a 400 ohm amplifier: Np/Ns = (Zp/Zs)^0.5 = (400/8)^0.5 = 7 I must confess I have no idea how many windings real transformers have; do not go by my numbers. Somewhere I have a book that has information on designing transformers if you need more info I will try to find it. -
I would think if the larger rated relays failed then the smaller rated relays would not last as long. Have you tried looking on Ebay for replacements? I have had good luck recently finding replacement parts on Ebay. Sorry I can not be more helpful to you; good luck.
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Help interpreting Circuit schema please...
HarryA replied to giph's topic in Electronic Projects Design/Ideas
At the lower left the component would be a 1500/1k5 resistor like the one at the lower right. The LEDs indicate which coil/output is active. At the upper right the symbol looks like a ground off the signal generator. The LEDs are represented by the white dots on the front panel above the words OUT perhaps? P1 and P2 look odd; they have the potential of shorting the inputs. At P2 with the wiper all the way down the input would be shorted circuited. -
If you do not need SMD perhaps "The LT138A/LT338A (LM138/LM338) series of adjustable regulators provide 5A output current over an output voltage range of 1.2V to 32V." The LM338 is about 1$ each on ebay.
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Search on ebay for "personal alarm switch" most do not have a switch just a pin you pull out. I used one to find the blockage in a drain pipe. They are LOUD!
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Power Strip with USB, Surge Protector Smart 3 Outlet and 4 USB Port Charger with 5ft Extension Power Cord 1250W 100-240V https://www.amazon.com/Protector-Extension-100-240V-Portable-Transformers/dp/B07KGPFHYC/ref=sr_1_9?s=electronics&ie=UTF8&qid=1548959567&sr=1-9&keywords=surge+protectors+for+computers I worked with a power supply that was 900 amperes and 8 volts; this would not work for that
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Amplify the smartphone headphone port voltage
HarryA replied to Yasas_Weerasinghe's topic in Electronics chit chat
This maybe helpful: How to make an IR blaster: https://www.instructables.com/id/How-to-Make-an-IR-Blaster/ and an amplifier https://www.amazon.com/Geekroom-Headphone-Amplifier-Rechargable-Computers-Black/dp/B07F1JS4JV/ref=sr_1_21?ie=UTF8&qid=1548463071&sr=8-21&keywords=cell+phone+audio+amplifier This is an old question but it maybe helpful to someone in the future. -
audioguru is correct. But if you are interested in cell phones you may find this site helpful: https://www.instructables.com/id/Make-your-own-cellphone-from-scratch/
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Wanted: Activity Reminder Device
HarryA replied to donwiss's topic in Electronic Projects Design/Ideas
I would use an arduino microcomputer with an arduino display shield for the display. The best microcomputers are about 22$ down to a few dollars for the ones from China. The arduino display shields are around 10$ or so. The Utlransonic distance measuring transducer senors are less than 10$; they detect if you are in your seat or not. https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=arduino+uno https://www.amazon.com/s/ref=nb_sb_ss_i_1_13?url=search-alias%3Daps&field-keywords=arduino+ping+sensor&sprefix=arduino+ping+%2Caps%2C215&crid=DDBCCF7NH7CK https://www.amazon.com/s/?ie=UTF8&keywords=arduino+display+shield&tag=geminipcstand-20&index=aps&hvadid=28314448797&hvqmt=e&hvbmt=e&hvdev=c&ref=pd_sl_83ujuhent2_e -
Changing just the AC Frequency
HarryA replied to Tingobap's topic in Electronic Projects Design/Ideas
One can go from 50hz ac to 12 vdc via battery charger then from 12 vdc battery to 60hz 120v via a dc to ac converter. see: https://www.bing.com/videos/search?q=50hz+to+60hz+converter&&view=detail&mid=3D9219028DABBB0162A53D9219028DABBB0162A5&&FORM=VDRVRV&ajf=60 -
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Hello, I would think few of us would know anything about mig welders. I gather you want to hot switch the current from the mains to the welder. What current does your welder draw would be a start. You may need a high current relay to do the switching. Like? https://www.grainger.com/product/5ZH38?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!166591437759!!!g!81032003877!&ef_id=WqqIQwAAAacd4m57:20180315145043:s It's rated "AC contract rating - relay: 25 amperes at 240 volts ac." You need a relay rated higher than it draws off the mains because of the inductive load - I gather the mig welders have a transformer at the input like an arc welder?
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How about 3 terminal adjustable voltage regulators? see for example: https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/LM317AHVT?qs=%2fha2pyFadugRpOCsw7uJG%2fYkcWjLe5SQfHkipQZSRvGAuHf8Q8Z20lpgQCwyK1vllMxUP7WNhWIGj0RAnAK1dQ%3d%3d 60 volts max and 1.5 amperes. Poke around at Mouser for higher current ones also. There are filters on their site that are helpful.
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how to design a battery jack for unknow phones
HarryA replied to mohamad7419's topic in Power Electronics
Your " unknown phone " is unknown to us also. One photo is worth a thousand words, two photos are worth two thousand words, etc -
You need to define this so someone can help you.
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The power required by the charger would be in the order of: 120 * 0.3 = 36 watts. The 220/240 To 110/120 Volt European Socket Power Converter Step Down Transformer off ebay.com are rated 100 watts and not expensive. Order one directly from China; it's just up the big pond from you
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I enlarged the image off the Amazon.com but could not read it https://www.amazon.com/Black-Decker-LCS1620-Lithium-battery/dp/B01M6TQPY2/ref=sr_1_3/141-0275392-4037060?ie=UTF8&qid=1499813460&sr=8-3&keywords=Black+%26+Decker+LCS1620 ...but ebay.com has a readable image http://www.ebay.com/itm/Black-Decker-LCS1620-20v-20-Volt-Lithum-Ion-Battery-Charger-NEW-/272090041874?epid=1640405275&hash=item3f59d48e12:g:mf8AAOSwawpXr3eh 120v @60hz 300ma
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" which one is right? " What two are you comparing?
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This unit will work stand alone (with out a UNO) and has wifi> https://www.amazon.com/HiLetgo-Version-NodeMCU-Internet-Development/dp/B010O1G1ES/ref=sr_1_22/136-5999016-8336545?ie=UTF8&qid=1496770085&sr=8-22-spons&keywords=arduino+wifi&psc=1 Read the Q/A section.
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What microcontroller should I use for my project?
HarryA replied to nav15's topic in Electronic Projects Design/Ideas
If you search on amazon.com for "arduino wearables" you will find a number of devices. There are also a number of books on the subject.- 1 reply
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- gyro
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I gather if you want 1.8 volts out you buy the LP3853ET-1.8/NOPB and if you want say 2.5 volts you buy the the LP3853ET-2.5/NOPB chip and so forth. They must define the input voltages for each somewhere? What do you mean by "Can I use LP3856 here ?" ? What is your application?