Turns ratio on a 70V 10W Line matching transformer??

Started by royalmp2001 in sci.electronics.basics11 years ago 10 replies

I have come across a project that uses an old Radio Shack 70V 10W Line transformer. The primary has taps for "C", 10W, 5W, 2.5W, 1.25W and...

I have come across a project that uses an old Radio Shack 70V 10W Line transformer. The primary has taps for "C", 10W, 5W, 2.5W, 1.25W and 0.62W The secondary has taps for "C", 4ohms, 8Ohms and 16Ohms. What is the turns ratio if the 5W and 0.62W taps only are used on the primary and the "C" and 16Ohms taps are used on the secondary? How is it calculated?? THanks


High Voltage AC to DC

Started by ZhangLu in sci.electronics.basics11 years ago 3 replies

Hi all, I need high voltage DC of very small amp. So I used IC 555 to produce the fluctuating current and step up using a radio transformer to...

Hi all, I need high voltage DC of very small amp. So I used IC 555 to produce the fluctuating current and step up using a radio transformer to high AC voltage, to about 2Kv. How do I go about converting this high voltage AC to high voltage DC? TQ Newbie


Negative ion generators

Started by Technician in sci.electronics.basics11 years ago 12 replies

Hi all, I hope you can assist me with some questions about negative ion generators and ozone production. Firstly, I've been searching for...

Hi all, I hope you can assist me with some questions about negative ion generators and ozone production. Firstly, I've been searching for some schematics (with no luck,I can only find flyback transformer ccts and cockroft walton types of ccts) for those commercial negative ion generators (not ozone generators) you often see at the source or on ebay that utilize a metal plate to collect...


Transformer Help

Started by Jim Douglas in sci.electronics.basics11 years ago 6 replies

I am looking to replace a transformer for a rechargeable razor which was plugged into 220V by accident, not me the kid. It's...

I am looking to replace a transformer for a rechargeable razor which was plugged into 220V by accident, not me the kid. It's marked File:0326-3501-01 I/P 120V O/P 3.8V 110mA Gooogle showed little and searching Mouser and a couple of others didn't find anything even close? Any help is appreciated. I still have to run to the local surplus electronics store but they are closed today!...


In what ways can a transformer fail....?

Started by royalmp2001 in sci.electronics.basics11 years ago 63 replies

Hi everyone, I am looking at safety issues concerning transformers. Basic question, I know, but other than an open circuit due to a winding...

Hi everyone, I am looking at safety issues concerning transformers. Basic question, I know, but other than an open circuit due to a winding burnout, or maybe a shorted turn, how else can a transformer fail? Is it likely/possible that the primary voltage of a mains step-down transformer can appear on the secondary due to some fault? I have a transformer that has an oval core encapsul...


Transformer drawing 1 amp

Started by Anonymous in sci.electronics.basics11 years ago 36 replies

I have a transformer that is drawing about 1 amp when the secondary is not in use. Is this normal? Its a 15amp 12V CT transformer. ...

I have a transformer that is drawing about 1 amp when the secondary is not in use. Is this normal? Its a 15amp 12V CT transformer. The secondaries read 12 volts from the center like it should(its actually about 13V). It had what I guess what a thermistor(a rectangular box that as stuck inside the transformers windings) but I took it out because I thought it might be the problem. It hums...


AC motor control via "dimmers"

Started by les in sci.electronics.basics10 years ago 18 replies

Hello..... I was just at Home Depot trying looking for a quick fix to a problem. I need to slow down an AC fan motor (measured at 2.3 A...

Hello..... I was just at Home Depot trying looking for a quick fix to a problem. I need to slow down an AC fan motor (measured at 2.3 A full speed/ 120V.) I was finding all ceiling fan controls are rated at 1.5 A. max. But then I found in the back some other lighting controllers that were unusual. One was for low-voltage magnetic and the other electronic transformer types. It connects to th...


Power Supply Rectification and Smoothing

Started by Anonymous in sci.electronics.basics10 years ago 93 replies

I'm building a power supply for a 36V, 500W DC motor to drive a small lathe. I have scrounged a transformer from an old microwave oven and...

I'm building a power supply for a 36V, 500W DC motor to drive a small lathe. I have scrounged a transformer from an old microwave oven and removed the 2000V secondary windings leaving the 240V primary windings intact and undamaged (I will test with a megger before powering up.) I will wind some 30A automotive flex around the secondary core and test until I have around 36V (the rated volt...


What are the properties of an Lt44 transformer, And where can I get one?

Started by will in sci.electronics.basics10 years ago 1 reply

If anyone could tell me where to get an lt44 transformer or equivalent, that would be great! If you could also give me the properties, that...

If anyone could tell me where to get an lt44 transformer or equivalent, that would be great! If you could also give me the properties, that would be even better! Thanks!


troubleshooting method for micro-controller board ?

Started by robb in sci.electronics.basics10 years ago 102 replies

i have a micro-controller board with 3 big 40DIP ICs, 10 or so 16 DIP support ICs. with 32v/8v/5v transformer supply that connects to two bridge...

i have a micro-controller board with 3 big 40DIP ICs, 10 or so 16 DIP support ICs. with 32v/8v/5v transformer supply that connects to two bridge rectifiers {32v, 8v}a fuse links sit between transformer and rectifiers, no schematic. i believe the 32v shorted with 5V line and it blew one fuse link. the fuse link was replaced with same and when powered all three fuses blown. So....where d...


What limits the current in an unloaded transformer?

Started by FunFred in sci.electronics.basics10 years ago 7 replies

I got to do some experiments recentley and I realise that my understanding of transformers has some holes..... First I got hold of a variac...

I got to do some experiments recentley and I realise that my understanding of transformers has some holes..... First I got hold of a variac and some resistor loads which I attached to the transformer. The transformer got hot, but not too hot, not much new there. When I wound up the input voltage to the primary it got hotter. OK so far... Then as I was in a hurry and I wanted to test s...


Increase AC mains frequency?

Started by Anonymous in sci.electronics.basics10 years ago 18 replies

If the power companies increased the frequency of AC mains current from 60 Hz to something more like 1 kHz, would this make transformer sizes...

If the power companies increased the frequency of AC mains current from 60 Hz to something more like 1 kHz, would this make transformer sizes smaller for AC equipment? Besides older-style AC clocks no longer keeping correct time, what would the downside to increased AC frequency be? Michael


How can I convert 240v to 220v

Started by Anonymous in sci.electronics.basics10 years ago 9 replies

I bought some electrical sensitive equipment from overseas which runs on 220v. I tried to run it on 240v in Australia and some of the resistors...

I bought some electrical sensitive equipment from overseas which runs on 220v. I tried to run it on 240v in Australia and some of the resistors have been burned. I know it will damage the equipment to run on 240v but cannot find a transformer to convert from 240v to 220v. Any advice on this? Thank you.


Need Voltage Doubler Circuit

Started by Dave.H in sci.electronics.basics10 years ago 26 replies

I have a regen radio powered by two 23 volt wallwarts in series, but would like to use a 24 VAC transformer with a voltage doubler to provide...

I have a regen radio powered by two 23 volt wallwarts in series, but would like to use a 24 VAC transformer with a voltage doubler to provide the 45v B+, I've found circuits via Google, but they don't give the values for 24 VAC. Also don't say what diode to use. I have about 50 1N4004's lying around I could use. Transformer I'm planning on using is M6672 @ www.dse.com.au Thanks Dave


300 ohm to 75 ohm impedance matching "transformer"

Started by Joe in sci.electronics.basics9 years ago 3 replies

I bought a 300 to 75 ohm "matching transformer" to hook up to a home built TV antenna. The matching transformer looks exactly like the one on...

I bought a 300 to 75 ohm "matching transformer" to hook up to a home built TV antenna. The matching transformer looks exactly like the one on this URL: http://www.solidsignal.com/prod_display.asp?PROD=WMXFMRPT I have a couple of questions: Can these matching transformers be used in either direction? That is, my antenna will get the 300 ohm end, and the TV antenna input will get the ...


Calculating DC Output Current From Unregulated AC Transformer

Started by Anonymous in sci.electronics.basics9 years ago 69 replies

I have an application in which I need to determine if a transformer is suitable. Transformer is rated for 12VAC, 1.67A but I need DC. I could...

I have an application in which I need to determine if a transformer is suitable. Transformer is rated for 12VAC, 1.67A but I need DC. I could put a bridge rectifier and capacitor after it easily enough but how does one go about calculating the DC output this is capable of? I've previously used a x 1.41 factor to convert which would give 16.92V, minus the forward drop of a couple silicon...


Dialer problem with a picchip

Started by lerameur in sci.electronics.basics9 years ago 31 replies

Hello, I have a recuring problem when connecting my circuit to the phone line. basically the circuit I use is...

Hello, I have a recuring problem when connecting my circuit to the phone line. basically the circuit I use is : http://ourworld.compuserve.com/homepages/Bill_Bowden/autocall.htm with the exception that I connect B3 to an 8th order low pass filter and the output of that goes to the positive of the transformer. Also I use picbasic to create my DTMF. I connected a small audio speaker to th...


Are A/V receivers good source for transformers for PSU?

Started by Hammy in sci.electronics.basics9 years ago 2 replies

I've been looking for a suitable transformer for building a 300W PSU 0-30V @ 0-10A. My 2.5A one just isn't cutting it anymore. I already have...

I've been looking for a suitable transformer for building a 300W PSU 0-30V @ 0-10A. My 2.5A one just isn't cutting it anymore. I already have everything I need with the exception of the transformer. I was wondering if older A/V receivers would be a good place to scrounge a transformer. There's a couple of pawnshops in town that sell old ones for anywhere from $20 bucks and up. How could I ...


Transformer Current

Started by Anonymous in sci.electronics.basics9 years ago 15 replies

Nutshell: I have a lead acid 12V battery charging device that used a wall transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The...

Nutshell: I have a lead acid 12V battery charging device that used a wall transformer rated as 120 VAC 26W input, 12 VAC 1.6A out. The xformer failed (primary opened) and I made a replacement (12.6 VAC 3A out) but it is drawing 4.5A and blowing the secondary fuses I put in place. Synopsis: I have two "Basement Watchdog" battery operated sump pumps. The batteries are 6 cell 12V lead ac...


What is a unbalanced AC transformer?

Started by Uriah in sci.electronics.basics8 years ago 4 replies

I need to provide a 10VAC power supply to a cirris cable tester and they said it was unbalanced. It is a three pin input with the center being...

I need to provide a 10VAC power supply to a cirris cable tester and they said it was unbalanced. It is a three pin input with the center being neutral and each side is hot 10VAC but it is unbalanced. What do they mean by unbalanced? How would I wire that up? And is there a way to tell how to wire it in from looking at the device, I don't have the that power supply. Thanks Russ