European transistor conversions

[RSmikh]

I got a electrical wiring diagram from my dads friend for a device that he wants me to build for him but the wiring diagram is from Ukraine and i can not seem to be able to find any of the transistors for the device, If anyone can help it would be great. The numbers are KT835, KT827, and a KT315. If anyone can help me find where I can convert those numbers into american numbers it would be greatly appreciated. Thanks for your help

 

[Bob S]

See
http://pdf1.alldatasheet.com/datasheet-pdf/view/146705/OPTEK/KT835L11.html

 

[RSmikh]

thanks for that website but i can figure out how to us it or where i can buy one of those transistors any ways

 

[berkeman]

I got a electrical wiring diagram from my dads friend for a device that he wants me to build for him but the wiring diagram is from Ukraine and i can not seem to be able to find any of the transistors for the device, If anyone can help it would be great. The numbers are KT835, KT827, and a KT315. If anyone can help me find where I can convert those numbers into american numbers it would be greatly appreciated. Thanks for your help

Can you post the schematic? We could probably suggest some alternate parts to use. Also, I was looking at that datasheet link earlier, and it's for a slotted optical sensor with transistor output. Is that what the KT835 is on your schematic? If not, it may just be a google hit thing.

 

[RSmikh]

I will try to get the schematic scanned into the computer and uploaded as soon as I can. Thanks for all your help.

 

[RSmikh]

here is the schematic. let me know if you guys have any ideas that might work in place of the transistors.

 

[Bob S]

Hi RSmikh
The KT835 is an optotransistor-optoisolator with a 2-terminal output (collector-emitter). This is not used in your schematic at the location shown.
Bob S.

 

[uart]

That thing's a simple square wave inverter right? Anyway they're all just general purpose/power npn transistors.

For the kt315 use just about any low power npn type. I'd use BC337.

For the kt835 use just about any medium power npn. I'd use BD139 or similar.

For the kt827 you need a power transistor. Without more circuit details I can't say for sure but probably rated at least 10Amps and 30 volts. It's been a while since I've use power transistor so I can't recommend a part off the top of my head - these days it's all mosfets for that type of application.

BTW. That looks like a pretty old design. You know you could replace the kt835, and the 22R resistor, and the kt827 and the anti-parallel diode all with a single n-channel mosfet! It would probably be cheaper more efficent and more reliable. Something like IRL2703 would be perfect (as would many other similar power mosfets) : https://ec.irf.com/v6/en/US/adirect/ir?cmd=catProductDetailFrame&productID=IRL2703PBF

 

[f95toli]

My guess is that they are referring using old Soviet designations.
There is no such thing as "European" transistors; in western Europe (and after the collapse of the Soviet union the east as well) the designations (and the components, since they are made in the Far East) are exactly the same as in the US. Nowadays engineers in Ukraine use exactly the same components as the rest of the world so presumably the schematic is quite old.

There are a few DIY sites around where people discuss old Eastern Block electronics (radios, hi-fi etc), maybe you can find a table somewhere which lists equivalent.

 

[RSmikh]

the schematic is at least 50 years old from what i know because my grandfather got it when he worked at a nuclear power plant back in Ukraine, before we moved to America. If anyone knows where I can find a chart to find the equivalent let me know, mean while I will try to find one myself but maybe one of you guys knows of a good one let me know. Thanks

 

[berkeman]

the schematic is at least 50 years old from what i know because my grandfather got it when he worked at a nuclear power plant back in Ukraine, before we moved to America. If anyone knows where I can find a chart to find the equivalent let me know, mean while I will try to find one myself but maybe one of you guys knows of a good one let me know. Thanks

FYI, the BJT was invented about 50 yeas ago, and not in the Ukraine...

EDIT -- reference: http://en.wikipedia.org/wiki/Transistor

.

 

[RSmikh]

If I did try to use the MOSFET idea does it still get hooked up the same way as the transistors do. Would they have 1 on Mouser.com since that is where I get all of my electrical components. I am not all that great with electronics but so if you guys can help me that would be great thanks.

 

[uart]

If I did try to use the MOSFET idea does it still get hooked up the same way as the transistors do. Would they have 1 on Mouser.com since that is where I get all of my electrical components. I am not all that great with electronics but so if you guys can help me that would be great thanks.

If you're still looking for replacement transistors then the two I mentioned above will definitely work ok. The power transistor (kt827 replacement) is the hardest case because the current-gain is an important factor. A readily available option would be TIP3055 and I'm pretty sure it would do the job ok as long as the current is under about 6 Amps.

If you want to try a mosfet replacement then remove components kt835, 22 ohms, kt827 and the diode from the circuit and replace with power mosfet as follows.

- mosfet drain connects to where kt827 collector was previously connected.
- mosfet source connects to where kt827 emitter was previously connected.
- mosfet gate connects to where kt835 base was previously connected.
- Add an extra 1k resistor from gate to source to simulate the base current in kt835 as this current has an influence on the oscilator period.

You would also benefit from adding some series resistance (say approx 1k) in each of the cross-coupled bases of the kt315 (bc337) but this is optional. (this would be a benefit even if you used the original transistors, it speeds up the rise time of the base/gate drive and reduces switching losses).

BTW. I think there is an error in the schematic. On the left hand side the 27k and 330 ohm pull-up resistors are interchanged. The 27k resistor should be on the base side of the capacitor and the 330 ohms on the collector side.

 

[RSmikh]

the resistance should stay below 6 amps since the original power source has only 10 amps. I might try both options and see how it works out if anyone has any other ideas or better solutions let me know. Thanks for all your help.

 

[RSmikh]

one last question, just wondering what would L1, L2, and L3 be is it just coils of some sort or would it be a a step up transformer.

 

[Redbelly98]

Looks like a step-down transformer with center-tap. L3 is the primary coil, L1 and L2 the secondary.

Do you want to build for 220V or 110V input? Either way, you'd want to know what the transformer output is supposed to be. Maybe some of the other folks in here can figure that out.

 

[uart]

one last question, just wondering what would L1, L2, and L3 be is it just coils of some sort or would it be a a step up transformer.

Ok so you don't actually know what this circuit is for, is that correct?

Because my best guess is that this circuit is a very simple 12V to 220 volt inverter. This would make L1:L2:L3 a 12:12:220 volt step-up transformer with center-tapped primary. It should have as low as possible leakage inductance (that is, very good magnetic coupling) and it's extremely important that you get the relative phasing correct on the two primaries.

 

[RSmikh]

the diagram says that the battery is supposed to be 12volts for the power source and since i realize that most of you can not read Ukraine the side notes in the top right say that L1 and L2 are 1.5mm devices rated at 17 each and L3 is a.3mm device rated at 700. which is why i could not figure out exactly what they were trying to use there.

 

[uart]

the diagram says that the battery is supposed to be 12volts for the power source and since i realize that most of you can not read Ukraine the side notes in the top right say that L1 and L2 are 1.5mm devices rated at 17 each and L3 is a.3mm device rated at 700. which is why i could not figure out exactly what they were trying to use there.

Ok that will be the number of turns. I'd wind the 700 turn secondary onto the bobbin first, then add an insulation layer, and then wind L1 and L2 bi-filar (take the two lengths of wire side by side and wind 17 turns of both at the same time). Do they specify what core to use?

 

[Redbelly98]

Looks like a step-down transformer with center-tap. L3 is the primary coil, L1 and L2 the secondary.

Oops, I had that backwards. Sorry!

 

[vk6kro]

The output of this device would be a 55 Hz (approx) square wave.
This would be a noise generator and likely to interfere with radio and TV reception.
You could build it anyway as a tribute to your grandfather, but be aware of the possibility of interference.

The turns ratio given suggests that they used a 12 volt centre tapped primary (ie 6 volts plus 6 volts) and a 250 volt secondary. (17 / 700 * 250 = 6.07 volts)
Such transformers would be rare in the US, but 110 V to 6 V + 6 V secondaries would possibly be available unless you especially wanted 250 Volts.

 

[RSmikh]

does anyone know where i might be able to find a transformer like that. The interference really will not make a difference because the guy that i am building it for lives in Ukraine and his closest neighbor is 10 miles away from him so it will be fine.

 

[Bob S]

Here are two thumbnails showing the performance of the inverter circuit. The circuit includes several extra components to facilitate turn-on in SPICE, as well as discharging npn bases when the transistors should be off. No LEDs are shown. The output transformer has two 200 mH primary windings and a 80-Henry secondary winding. There is about 22 volts across the output transistors when the collectors are open. The simulation shows about 215 volts (red, left scale) and 480 milliamps (black, right scale) across the output load, equivalent to about [STRIKE]230[/STRIKE] 100 watts. The frequency is about 65 Hz.
Bob S
[Edit] Here is a possible source for output transformers. These are ordinarily dual 117 V primary, 12 to 14 v secondary dual windings, 95 VA to about 200 VA, 50/60 Hz. I have not checked prices.
http://www.amveco.com/pdf/Amveco_Catalog.pdf#page=18

 

[vk6kro]

Love those simulations, Bob.

Just a couple of queries.

The output transistors have different type numbers on them. Is there a reason for this?

What was the input current from the 12 V battery with your 100 watt load?

Could you try a few capacitors across the load to see if the waveform rise-times could be increased without too much effect on efficiency? It is a real harmonic generator as it stands.

 

[Bob S]

Love those simulations, Bob.
Just a couple of queries.
The output transistors have different type numbers on them. Is there a reason for this?.

My error--- They were both supposed to be FZT849, but I don't have a good selection of BJTs in LTSPICE IV. The 2N3055 didn't work at all. The FZT849 is rated at 7 amps continuous, and has a difficult package to mount.

What was the input current from the 12 V battery with your 100 watt load?.

About 9.2 to 9.4 amps, and varied during cycle.

Could you try a few capacitors across the load to see if the waveform rise-times could be increased without too much effect on efficiency? It is a real harmonic generator as it stands.

The FZT849 worked on 1 uF but not 2 uF across the output load (480 ohms). A FDR4420A nmos MOSFET worked at 2 uF but not 5 uF.

[Added note] The turns ratio for the output transformer is L1:L2:L3 =1:1:20. The inductances are 0.2H:0.2H:80H.
Bob S

 

[vk6kro]

Thanks Bob.

Looks like a bit of filtering of the output might be OK. Maybe a high voltage 0.47 uF or similar.

 

[Bob S]

Thanks Bob. Looks like a bit of filtering of the output might be OK. Maybe a high voltage 0.47 uF or similar.

All it will do is round the corners a little.
Bob S

 

[vk6kro]

Thanks Bob,
I wondered how it would affect the rise time of the output square waves? Would LTSpice show an expanded version of the rise time with a capacitor across the output?

This one is just for curiosity. Could you try a 0.075 uF capacitor across the 80 H secondary?
Should resonate, but maybe not with the 100 watt load on it. Maybe without.

I guess the real solution is to drive it with a sinewave instead of trying to turn a square wave into a sinewave a high power levels.

 

[RSmikh]

does anyone know where i can get a transformer like that or maybe how i can make my own.

 

[vk6kro]

Transformers are heavy so you need to look in your local yellow pages and buy it locally.

If it is going to be used in the Ukraine, they use 220 volts so you would need the 220 volt version of the transformer. Also, there is going to be postage to Ukraine.

Could you check on the availability of Chinese or Indian made sinewave inverters in the Ukraine? Your friend may be able to get a nice shiny new one for the cost of something you spend hours making.

 

[RSmikh]

does anyone know how i can make my own transformer since we can not find one all ready made anywhere. and where i can find those capacitors on that schematic cause i can only find the polarity sensitive one in the bottom center o the board.

 

[vk6kro]

Those capacitors are commonly available.

If you pull apart an existing transformer, count the turns of wire as you unwind them. Save all the hardware like insulation and terminal connection strips. These might be hard to replace.

Then you can work out a "turns per volt" figure for the transformer. This is often a figure like 3, 4 or 5.
Then calculate the new number of turns for the output voltage you want.

It will be obvious that if you put more turns of wire into the same space, the wire might have to be thinner for it to fit.

Also, you cannot depend on the insulation on the wire to isolate windings from each other. This applies particularly to the mains winding. The best transformers have the mains winding and the other windings on different plastic frames so that leakage between the windings is much more unlikely.