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Old 04 June 2012, 10:53   #1
DDNI
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Speedy. The variable speed accellerator.

Has anyone ever tried one of these variable speed oscillators on an amiga accellerator?

http://www.micromac.com/products/speedy.html
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Old 04 June 2012, 11:53   #2
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i was looking for one of these a few months back,does anyone know the frequency range of one of these?

it would have to work(adjustable) between 50-120mhz in my case.

and what are the incraments between frequencys i wonder.
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Old 04 June 2012, 11:59   #3
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Looking at the table on the link, 30 - 125mhz is the range. It also seems to be fine enough to deliver speeds which involve single unit changes.

Availability is my big question. The link is old...
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Old 04 June 2012, 12:03   #4
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yeah thats what im worried about,the link is pretty old.

it should work as it replaces the can oscillator,and it is 5 volt and ttl by the look of it.
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Old 04 June 2012, 12:42   #5
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One of these devices from Linear Technology would work,
http://www.linear.com/product/LTC6905
and you can purchase it from Farnell.

A small PCB and it could fit 8/14 pin DIL sockets.

Ian
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Old 04 June 2012, 13:00   #6
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looks interesting i might give one of these a go stedy.
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Old 06 June 2012, 22:59   #7
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Hi,

Just checked the workshop stores, I have a couple of LTC6907 (40KHz to 4 MHz), bought for another project I will test shortly. The 1-2% accuracy does concern me a little but for a CPU it should be OK. I typically use around 0.0035% accuracy crystals.

Will report back with test results.

Ian
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Old 06 June 2012, 23:31   #8
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hi stedy,do you think it would be better to run a LTC6905 on 3.3 volts rather than 5 volts.
i dont know how it will fair between 50 and 110mhz.
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Old 18 June 2012, 20:53   #9
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Hi,

I tested the LTC6907 device I had and was pleased with the results. Initial frequency accuracy was within tolerance (0.7% compared to a potential 1%) and waveform shape/symmetry was good. Would like to try it with some 0.1% resistors, when I buy some.

@roy bates
The LTC6905 can use 3.3V or 5V, which is great. The 68060 is 3.3V and I would expect the clock source to also be 3.3V LVTTL. My only concern with using 3.3V with a 5V part, is if the CPU or CPLD has HCMOS inputs, so requires 3.33V minimum (66% of 5V) for a logic 1. Would need to check all potential devices.

Using the LTC6905 is easy enough though. Could easily make some adaptors, if there was the demand.

Ian
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Old 18 June 2012, 21:33   #10
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it shouldent be a problem really, all 040 and 060 cards oscilators on amigas are 5 volts ,i was just wondering if it could be run on 3.33 volts and still be usable.
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