# Transistor balanced wheel clock driving circuit

#### ranatungawk

Joined Oct 30, 2008
188
These two are driving-circuits of Old Transistor balanced wheel clocks. As below, there are two type of circuits. Could you please explain me what is the purpose of resister “X” .. why two type of arrangement ? what is the most effective circuit ?

#### Dodgydave

Joined Jun 22, 2012
10,306
In number 1 the resistor biases the transistor directly from the battery supply, so it's quicker to turn on , whereas in number 2 it's connected through the coils, so the back emf will switch it off faster , i would say number 2 is the best circuit.

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#### ranatungawk

Joined Oct 30, 2008
188
In number 1 the resistor biases the transistor directly from the battery supply, so it's easier to turn on , whereas in number 2 it's connected through the coils, so the back emf will switch it off faster , i would say number 2 is the best circuit.
Thanks for the information:

in both cases, Is the swing of the balanced wheel same ?

#### Ya’akov

Joined Jan 27, 2019
5,660
I am guessing that the choice of circuit might matter depending on the construction of the wheel. One would “kick“ the wheel harder, the other let go more suddenly.

#### ranatungawk

Joined Oct 30, 2008
188
I am guessing that the choice of circuit might matter depending on the construction of the wheel. One would “kick“ the wheel harder, the other let go more suddenly.
Thanks!

is it ..

1. let go more suddenly
2. “kick“ the wheel harder?

#### Ya’akov

Joined Jan 27, 2019
5,660
Circuit 1 would turn on faster, circuit 2 would turn off faster. So, the reverse of your numbering.

#### ranatungawk

Joined Oct 30, 2008
188
Circuit 1 would turn on faster, circuit 2 would turn off faster. So, the reverse of your numbering.
I see,

so what is the best for a clock ?

#### Ya’akov

Joined Jan 27, 2019
5,660
I see,

so what is the best for a clock ?
I am guessing that the two circuits are illustrated because balance wheels do better with one or the other due to some aspect of their construction. So, if I am right, it would depend on the clock.

#### sparky 1

Joined Nov 3, 2018
717
The RLC oscillator circuit shown is simplistic and unregulated relying on the imagination to be a balanced wheel
for driving a clock that one would assume the mechanical clocks are somehow related.

#### ranatungawk

Joined Oct 30, 2008
188
The RLC oscillator circuit shown is simplistic and unregulated relying on the imagination to be a balanced wheel
for driving a clock that one would assume the mechanical clocks are somehow related.
This is correct ! even here, it runs a little fast or a little slow without any interference.

#### sparky 1

Joined Nov 3, 2018
717
Jun Ye explains where his experience with clocks has taken him.

#### AlbertHall

Joined Jun 4, 2014
12,023
I am guessing that the choice of circuit might matter depending on the construction of the wheel. One would “kick“ the wheel harder, the other let go more suddenly.
Does the kick attract the magnet or repel it?
Does which circuit is chosen depend on the answer to the above?

#### ranatungawk

Joined Oct 30, 2008
188
Does the kick attract the magnet or repel it?
Does which circuit is chosen depend on the answer to the above?
Does the kick attract the magnet or repel it? --- Don't both are same ???

#### AlbertHall

Joined Jun 4, 2014
12,023
Does the kick attract the magnet or repel it? --- Don't both are same ???
In one case the approach of the magnet towards the coil triggers the circuit and the magnet is attracted towards the coil. Then the coil current must be switched off quickly when the magnet is centred on the coil otherwise the coil will be opposing the magnet motion as it tries to move away from the coil.

In the other case the circuit is triggered quickly just after the magnet is centred on the coil and the coil repels the magnet to propel it on its way. Later the coil current is switched off but exactly when is less important.

In the first case the switch off should be fast but in the second case the switch on should be fast.

#### ranatungawk

Joined Oct 30, 2008
188
In one case the approach of the magnet towards the coil triggers the circuit and the magnet is attracted towards the coil. Then the coil current must be switched off quickly when the magnet is centred on the coil otherwise the coil will be opposing the magnet motion as it tries to move away from the coil.

In the other case the circuit is triggered quickly just after the magnet is centred on the coil and the coil repels the magnet to propel it on its way. Later the coil current is switched off but exactly when is less important.

In the first case the switch off should be fast but in the second case the switch on should be fast.
So what is the most important design for a clock ?

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#### AlbertHall

Joined Jun 4, 2014
12,023
So what is the most important design for a clock ?
No idea. That's why I asked the question.

#### ranatungawk

Joined Oct 30, 2008
188
No idea. That's why I asked the question.

#### BobTPH

Joined Jun 5, 2013
4,906
I think the answer is in post #8.

Bob

#### ranatungawk

Joined Oct 30, 2008
188
I think the answer is in post #8.

Bob
it's and open ended answer, i suppose. what will stop over swing of the balance wheel ?

#### BobTPH

Joined Jun 5, 2013
4,906
The spring and the the timing of the pulse. The entire electro-mechanical system must be considered.

Bob