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Argus25 · 2nd Aug 2018, 12:16 am

I think there is an issue that has not been addressed with the design (at least I cannot see it on the picture of the pcb). I'm surprised because the article I produced for making solid state vibrators for wireless sets, like the ZC1 (similar to the WS19) has been around for some years.

What is the issue ?

1) When a solid state vibrator circuit (which is force driven by an oscillator) switches the primary of a vibrator transformer, the existing value of the commutation capacitance (tuning capacitance value) on the transformer's primary is significantly inadequate and needs to be increased. Otherwise the voltage transients due to the transformer's leakage reactance threaten no only the switching devices, but also the transformer's insulation. The voltage transient magnitude will depend on the particular transformer and its existing tuning capacitances.

At least this is an easy fix, by placing a drain to drain capacitance of a suitable voltage rating and uF value, but I cannot see an added drain to drain capacitance in these units. This also reduces radio interference from the electronic unit, but it is fair to say any electronic version has much less of this than an electro-mechanical vibrator.

The relevant data on this issue is on pages 41 to 47 of this article, notice the text in RED on page 47. I made it like that so it would stand out and not get missed:

http://worldphaco.com/uploads/ZC1_MK...R_SUPPLIES.pdf

(Of note this issue does not apply to self oscillating circuit configurations)

Otherwise I think the physical design of the units look very good and nicely presented and probably better than any I have seen so far. The additional capacitance can always be added across the vibrator's socket pins.

(The voltage transients with a normally working electro-mechanical vibrator are actually lower than forced electronic switching because of the delay period where neither contact was closed, a dead band or timing gap. The resonant frequency of the transformer and tuning cap values chosen to allow good commutation with minimal overshoot. However, with mosfet and transistor switches, driven by an oscillator, with no significant dead band or timing gap used, the leakage reactance is a major issue, it is all in the article)

2nd Aug 2018, 12:16 am	#3
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Vibrators Solid State Replacements I think there is an issue that has not been addressed with the design (at least I cannot see it on the picture of the pcb). I'm surprised because the article I produced for making solid state vibrators for wireless sets, like the ZC1 (similar to the WS19) has been around for some years. What is the issue ? 1) When a solid state vibrator circuit (which is force driven by an oscillator) switches the primary of a vibrator transformer, the existing value of the commutation capacitance (tuning capacitance value) on the transformer's primary is significantly inadequate and needs to be increased. Otherwise the voltage transients due to the transformer's leakage reactance threaten no only the switching devices, but also the transformer's insulation. The voltage transient magnitude will depend on the particular transformer and its existing tuning capacitances. At least this is an easy fix, by placing a drain to drain capacitance of a suitable voltage rating and uF value, but I cannot see an added drain to drain capacitance in these units. This also reduces radio interference from the electronic unit, but it is fair to say any electronic version has much less of this than an electro-mechanical vibrator. The relevant data on this issue is on pages 41 to 47 of this article, notice the text in RED on page 47. I made it like that so it would stand out and not get missed: http://worldphaco.com/uploads/ZC1_MK...R_SUPPLIES.pdf (Of note this issue does not apply to self oscillating circuit configurations) Otherwise I think the physical design of the units look very good and nicely presented and probably better than any I have seen so far. The additional capacitance can always be added across the vibrator's socket pins. (The voltage transients with a normally working electro-mechanical vibrator are actually lower than forced electronic switching because of the delay period where neither contact was closed, a dead band or timing gap. The resonant frequency of the transformer and tuning cap values chosen to allow good commutation with minimal overshoot. However, with mosfet and transistor switches, driven by an oscillator, with no significant dead band or timing gap used, the leakage reactance is a major issue, it is all in the article)