Dinoplex AEC 101DA rebuild

Lars,
Not trying to be argumentative, but 10 to 20 kHz is quite easy to do with those transistors. They chose to do it that way for whatever reason. Perhaps it was simply because they found a ready made transformer that worked when they tried it. Most of the older CD ignitions of the era, and before this one came out, ran at frequencies higher than 5 kHz, at least the ones I have tested. The old Hyland that my father developed in 1962 ran at about 8 kHz using a small ferrite core. His later ones from about 1966 onward used a similar design to the Dinoplex power supply with an even smaller ferrite core and they ran at over 10kHz. Using the PNP counterpart (2N6609) to the 2N3773 I have built power supplies that easily run up to 18kHz with a small core.
The fact that many Dinoplexes are still running strong years later does show that it couldn't have been that badly designed. Nice that it was made to be rebuilt too, unlike the later AEC 103. Fred

 

Sorry to hear about the mishap, Andrew. Hope you can recover some of the power tools at least. Good that the Dino parts stayed safe, though! / Lars

 

The circuit appears to be straight out of the 1960’s RCA Designers Manual, showing a power converter to produce 120V 60 Hz AC from a 12 V battery. The slow turn-on that you cited in the previous post was probably exactly what the RCA designers intended: Gentle on the transistors and producing an output closer to a sine wave than a square wave.
The Dinoplex designers appear to have taken that circuit and scaled it up in frequency by a modest factor of 4 to 5. A very sensible and conservative approach, it seems to me. / Lars

 

lars,
Without scoping that power supply to be certain, it will produce a square wave (or mostly square) with rather large leading edge spikes. The spikes are precisely what gives that type of circuit the ability to produce a sufficiently high secondary voltage as the battery voltage falls. The spikes are larger as the frequency drops with a reduction in supply voltage, thus helping offset the reduction in supply voltage. A different design would allow fast turn on and off times for the transistors keeping the inherent voltage drop as low as possible (for lower I squared R losses in the transistor), and also keep the transistors from conducting any longer than necessary in the saturation region of the transformer. If the magnetic field isn't changing with current, then it is wasted as heat in the windings and the external circuit including the transistors. The right type of core material to reduce the effect of the inherent switching spikes and correct winding methods are a much more complex subject than I would have thought a few years ago. Maybe computer programs can figure it out consistently, but I doubt it. Fred

 

Fred, I am sure that everyone has had enough of the two of us by now, so I promise this will be my last comment on this subject:

No doubt it is producing a square wave, and no doubt it is an ugly one. No doubt it could have been made much better and much more efficient with the knowledge and the components we have today.

But I only wanted to point out that I see no obvious design violation with this circuit (that would explain transistor failures), and nothing that sets it apart from other similar designs from this era - including ones suggested by the transistor manufacturers.

But this is Andrew’s thread and it is about rebuilding the AEC 101. So let us allow him to continue to document his work, and let us save the theoretical discussions about inverter technology (old and new) for another time and place.


Andrew, sorry, I didn’t intend to step on your thread too much. I will be very interested to hear how your rebuild works out. It is an interesting thread for me - and many others, I am sure.

Lars

 

Lars, Yes we are getting off topic! My point however was that the technology existed long before the Dinoplex was made to produce lighter, more efficient power supplies and in fact this was being done by more than one manufacturer of CD ignitions, mosty in the USA. Fred

 

Should be easy enough to trigger it from the Pertronix 2. Do not connect any pertronix wires to the coil. Instead, connect the red pertronix wire to the same +12V feed to the CDI, and the black pertronix wire to the CDI wire that would normally connect to the points. Fred

 

Andrew, I am not trying to jump ahead of Fred here, but the answer is clearly: Yes, that would be a problem. You can not use the backup switch if you use any kind of electronic points triggering.

Any electronic trigger sensor would not be able to drive the coil directly. At best, you would not get any spark at all. At worst, you would instantly damage the sensor. It all depends on how it is internally protected and current limited. You would need to have an additional power transistor (similar to the early transistor ignitions) to do the switching in backup mode.

That is one reason why I insist on staying with mechanical breaker points. I like the system with a simple points triggered backup system. If there is a problem with currently available breaker points, it surely must be only temporary. High quality mechanical points distributors are being manufactured today for other marques, so it must be only a matter of time until the right manufacturer for our points are found. I understand why some may want to switch to electronic triggering, but I would never do it myself. A matter of personal preferences, I suppose. In my case it is also the desire to keep vintage equipment vintage, in addition to the ease of roadside repairs, etc.

In any case, it is nice to hear that your rebuild of the AEC 101 was successful. If it survived that long hot drive during your trip in Europe, it will probably survive anything.

 

Andrew, I admire your patience and entrepreneurship in order to keep the old technology running on new points. I am awaiting your development of good quality points and in the meantime I enjoy my trouble free conversion to a red ugly MSD box Never looked back.....

 

Andrew, I did not about these new Pertronics systems where also the power transistor is built in and hidden inside the distributor. Yes, that should work in backup mode.

Regarding the starter motors, I think you were wise to stay with the original one. My car had been provided with the modern gear reduction starter before I came into the picture. I did not like it but decided to keep it anyway. Well, it just broke down, despite only very few hours of use! So, newer is not always more reliable.

Nice photos, by the way. Your Dino picked a really beautiful spot to break down!

Best
Lars

 

What a neat, clean solution!

My previous objection to electronic triggering was that it appeared to prevent the use of the back-up ”emergenza” system. But since the Ignitor II module is designed to drive a coil directly, that objection goes out the door, I assume.

Using the Ignitor simply as trigger should only be beneficial, I believe. The clean, stable and bounce-free trigger pulses are probably making the Dinoplex a bit less nervous than usual. Perhaps that is what you are feeling in your engine. Nice to hear!

I may not be in a rush to replace my old mechanical points yet, but it is nice to know that this alternative exists. With the experience you have had with your breaker points, I can certainly understand why you want to get rid of them. Nice work, Andrew.