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dubious soviet tacho generator ДГ-0,5ТВ
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Amper:
Hi!

I just came back from russia and i brought some NOS aircraft stuff with me, nothing fancy, just some switches, connectors and pots but also two little things i first thought were synchro resolvers by the looks of them. Turns out they are not. I took one apart and inside there is two independent asynchronous machines on the same shaft. One has two windings, the other three, they are built for 30V 400Hz but two phase @ 90° (both machines).

According to the datasheet and the units used it appears to me they are some sort of very accurate tacho generator used in analogue computers of the day measuring the speed of the gears inside, while potentiometers do the position work, this way having the derivative for calculating stuff.

however i just cant imagne the way they work, i have no schematic, i have no idea which coil has which function and how you can generate a DC output ffrom 400Hz this way.

I hope someone can help me out here...

This is the datasheet i fund, google translate helps a lot and seems to be accurate enough but it wont give much information, since they assume you already know what you are dealing with.

https://eandc.ru/pdf/dvigateli/dg.pdf

This is one taken apart, the rotor consists of two aluminium cylinders, the stators are inserted from opposite sides and the housing has an iron liner for the magnetics to have some path. (sorry for the bad image quality, pic was taken in a rush...)




ataradov:
I have not worked with them personally, so may be wrong. Basically you have two coils that need to be supplied two phases of 400 Hz that are 90 degrees apart. Those form a "stator" magnet. Then you have a control voltage that actually drives the rotor.

For the tachometer you have another coil that produces the sine or some other waveform that is dependent on the rotor position.

They are a nightmare to drive and not particularly accurate.
Amper:
Mh, It is not a motor, thats for sure, they are used to measure as the output in the datasheet is specified as mV/rpm. Also they are purely asynchronous, the rotor is 100% rotationally symmetric no way of using them for position sensing.
ataradov:
It is a motor-generator as suggested by the letter in the name. There is only one winding that's the output. I've seen that parameter in the table. I'm not really sure what that output looks like. It can't be a constant voltage, so that must be an amplitude of somehow modulated signal.
Amper:
Mh yes, in taht case you are right, though i also found this website:

https://auction.violity.com/99118108-dg-0-5ta-dvigatel-tahogenerator-primenyaetsya-v-sistemah-avtomaticheskogo-upr-leniya

and the last sentence of the second block says "For tracking systems with tachometric DC feedback and accurate integrating DC drives, DGs are used containing two-phase controlled asynchronous motors and TGP." which sounds exactly like the machine i have here.

The main reason why i think it can not be a motor is because it is commonly used in analogue computers, for example this piece from a mig29 contains similar devices in a slightly different package and a former mechanic / aircraft electrician i know confirmed this. Sadly he did not remember more than this...

https://youtu.be/iWrzVnKUCDk

They turn slowly and all parts are mechanically connected through gears.

I think the reason for having two asynchronous machines is for them to be counter acting keeping the system from producing torque, as soon as you turn the thing it will generate a voltage on the single sense winding. I will try this tomorrow, first of all i need a 90° power supply.
 
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