Hi Frank,
congratulations on your new acquisition! I think the Cricket! is the most exciting peripheral ever made for the Apple //c. Mine didn't come with a power supply either, but it would have been of no use in the EU anyways. Blake Patterson was so kind to take some pictures of the original supply on my request to get the original specs: https://www.flickr.com/photos/blakespot/14764818904/in/photolist-owFsW4-2odCjbm-ouDnk8-odqJeJ-q1t2uZ-kDaXD8-owFtpP-pYx9Ds-pYx9Bo-j7EYdj-ouVCut-ouHygb-odr4wF-ouHyRQ-odqJGs-ouTZK5-kDaW9V-kDbp7v-kDd7yC-2j4QZXu
It is not extremely sharp but it confirms what you have guessed: it is a 9v 500mA brick with a center positive plug. You can replace it with any generic wall wart with the same rating as long as it is not a switching power supply. I use a multi-voltage transformer for mine and it works... just of course a bit slower since we have 50Hz here.
The Cricket contains all necessary voltage regulators so there is no need for them in the power supply. The clock base is derived through a clever circuit based on a high-pass and a comparator that will extract the 120Hz ripple common to a full-bridge rectified DC supply. No need to take any extra precautions there. It should simply work.
I have collected some documentation and disk images related to it in the past. Feel free to browse my archive.org collection: https://archive.org/details/StreetElectronicsTheCricket
Have fun!
Yes it will run from a generic 9vdc supply, but doesn't keep timeThat's strange. You are sure that it is not a switching power supply?
correctly
that way.
using a 9v (AC) transformer and bridge rectifier. It may need a bit of additional smoothing in the power supply. I think there's only a 100uf capIndeed. 1000uF are actually better.
or two in the Cricket! itself.
There is a 555 chip as well, and if I hook it up to 14vdc or so it willThe 555 oscillator is used together with some inductors to generate the -5V required by the speech chip. The frequency is not critical for this application.
keep reasonable time. The speed of the clock seems to fluctuate a bit with the input voltage. I wondered if it was a backup time base or something.
Based on the regulator it should be ok up to 18 volts but I didn't want toThe potentiometer is used by the speech chip to set its RC oscillator
go that high. There's also a small potentiometer which I suspect may be related to a secondary time base.
you talked about. I put new electrolytic capacitors in mine so don'tGood idea. I have two and both stopped working because of some leaky capacitors.
really
want to open it back up again.
Yes it will run from a generic 9vdc supply, but doesn't keep time correctlyThat's strange. You are sure that it is not a switching power supply?
that way.
I think I have enough spare parts to try the circuit you suggest,
using a 9v (AC) transformer and bridge rectifier. It may need a bit of additional smoothing in the power supply. I think there's only a 100uf cap or two in the Cricket! itself.Indeed. 1000uF are actually better.
There is a 555 chip as well, and if I hook it up to 14vdc or so it will keep reasonable time. The speed of the clock seems to fluctuate a bit with the input voltage. I wondered if it was a backup time base or something.The 555 oscillator is used together with some inductors to generate the -5V required by the speech chip. The frequency is not critical for this application.
Based on the regulator it should be ok up to 18 volts but I didn't want to go that high. There's also a small potentiometer which I suspect may be related to a secondary time base.The potentiometer is used by the speech chip to set its RC oscillator frequency to about 160kHz.
you talked about. I put new electrolytic capacitors in mine so don't reallyGood idea. I have two and both stopped working because of some leaky capacitors.
want to open it back up again.
Yes it will run from a generic 9vdc supply, but doesn't keep time correctlyThat's strange. You are sure that it is not a switching power supply?
that way.
I think I have enough spare parts to try the circuit you suggest,
using a 9v (AC) transformer and bridge rectifier. It may need a bit of additional smoothing in the power supply. I think there's only a 100uf cap or two in the Cricket! itself.Indeed. 1000uF are actually better.
There is a 555 chip as well, and if I hook it up to 14vdc or so it will keep reasonable time. The speed of the clock seems to fluctuate a bit with the input voltage. I wondered if it was a backup time base or something.The 555 oscillator is used together with some inductors to generate the -5V required by the speech chip. The frequency is not critical for this application.
Based on the regulator it should be ok up to 18 volts but I didn't want to go that high. There's also a small potentiometer which I suspect may be related to a secondary time base.The potentiometer is used by the speech chip to set its RC oscillator frequency to about 160kHz.
you talked about. I put new electrolytic capacitors in mine so don't reallyGood idea. I have two and both stopped working because of some leaky capacitors.
want to open it back up again.
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