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Mehridian Sanders

So... wait... really? No power pass-through on Speech Synthesizer?

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ok, I was just perusing our own favored webstore, Arcade Shopper, and I read the description (who does that anymore?!?!), and I came to the part about external power not being necessary, if you mod the speech synth with 1 wire on 2 points. Pin 1. (Excellent Description). I am still ubernoob in the TI world, but the fact that this simple oversight on TI seems... ludicrous? Unless.... the peripherals connected beyond the SS would have been externally powered.

 

Well I will tell you what mod I am doing after I get home tonight!!

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The TI expansion port can't supply much power. At the time, the speech synthesizer was really all it could do. All the other sidecar peripherals DID contain their own power supply(hooray for power strips). So there was no point to a power passthrough on the syntesizer.

 

Here in the modern era, of course, 32k of RAM is basically nothing, and can probably be powered by good intentions alone.

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We all joke the TI's cartridge port area is the coffee warmer.  Perhaps we should all make this mod and remove the external PSU's from our expansion devices?

 

I like some eggs and bacon with my coffee.  ;-D

 

 

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1 hour ago, cbmeeks said:

We all joke the TI's cartridge port area is the coffee warmer.  Perhaps we should all make this mod and remove the external PSU's from our expansion devices?

 

I like some eggs and bacon with my coffee.  ;-D

 

 

In the "burrito" form factor please (the eggs and bacon, not the coffee).

Well I did the single wire across the SS Pin1  last night ... quick, maybe a bit dirty. Works fine and checked with Vmeter just to satisfy my own curiosity and check my own work .. seemed pretty solid = 5v. 

 

 

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27 minutes ago, tuf said:

Will this work to power stuff like NanoPEBs?

No!  NanoPEB's have 32K, RS-232, various floppy emulation circuits, and CF card to power.  Even the RS-232 varies based on V1 or V2, and probably the CF card (32MB - 4GB).

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a NanoPEB needs just 170 mA. Still this is outside the spec for the side port (50 mA? need a reference)

 

A USB battery pack with a USB-A to barrel jack, is quite safe and sufficient to run the NanoPEB for a while.

 

 

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11 hours ago, FarmerPotato said:

a NanoPEB needs just 170 mA. Still this is outside the spec for the side port (50 mA? need a reference)

 

TI-99/4A Console Technical Data, Section A.2, Page 6

 

P.S. It isn't the cup warmer capacity as much as where it is tapped w/o redundancy and trace size. So I suppose the overload TI refers to

is actually blowing the two feed traces from the +5V bus. ¯\_(ツ)_/¯

 

Doug

 

SideportSpec.JPG

5iport.JPG

Edited by helocast
Added P.S. attachment 2
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Notice the specs also indicate the power output is specifically for the speech module.  TI had a single purpose in mind for that and nothing more: "not intended for use by the consumer."  Pretty clear to me :)

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23 hours ago, FarmerPotato said:

a NanoPEB needs just 170 mA. Still this is outside the spec for the side port (50 mA? need a reference)

 

A USB battery pack with a USB-A to barrel jack, is quite safe and sufficient to run the NanoPEB for a while.

 

 

Nano requires a regulated supply. Just any 5v won't work well. I sell regulated supplies in my store

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Definitely please don't run a nano with an unregulated supply.  If you're lucky enough to have an old CF7+, they have a voltage regulator onboard... so you have some more flexibility there.  

 

That has been my only criticism of the nano.... no onboard voltage regulator.  Seems like a cheap enough part to make a drastic improvement to the longevity and stability of the device.  I bet people would happily pay an additional $20 per unit to have a regulator on board, and the part is less than a buck if you buy in volume.

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3 hours ago, arcadeshopper said:

Nano requires a regulated supply. Just any 5v won't work well. I sell regulated supplies in my store

Yup, and I do not recommend just any USB power source for the CF7 or nano.  I test my USB power sources for how well they hold their output under load.  Anything which drops under 5v at 1A gets pulled from the pile.  I found a couple of USB chargers which output a steady 5V up to 2A, and the voltage does not go up when not loaded.  Surprisingly, a cheap battery pack from WalMart has been nice and stable... I cannot recall the brand name but I use it for other devices, as well.

 

USB or otherwise, I definitely do not recommend anything cheap, especially cheap shyte from China.  Problems with those abound, such as high voltage (5.5V or more) when not under load, dropping under 5V when loaded above 500mA (I have seen some rated for 1A as low as 3.9V at 1A,) ridiculous amount of ripple, and my favorite is ground referenced to line input.

 

The other thing to watch for when using USB battery packs is the sense power.  Almost all of them turn "on" automatically, but to do this they can send anywhere from 2mA to upwards of 20mA of 5V down the line constantly.  I can use this sense current to charge up a smaller NiMH battery without the pack turning on.  This means that even when "off," there is still power flowing and you could potentially damage devices when connecting or disconnecting them.

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