This is a multi-part message in MIME format. --------------060404080904050403060003 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit davidwallace2000@comcast.net wrote: > The hardest part of a tape cassette interface is keeping the phase and > amplitude consistent across the frequency band. You MUST be using a > hi-fi recorder. Otherwise, you'll get significant zero-crossing shift > (which will make the pulse widths for zero and one different when you > have a sequence of "0,1"; a sequence of "0,0"; a sequence of "1,0" and > a sequence of "1,1". > > If you can, "loop back" from transmit data to receive data and see if > this "null tape device" will successfully transmit the data. If it > does, your recorder is probably at fault. If not, I have all the H8-5 > documents and a fairly good understanding of PLL technology. > > > > -------------- Original message -------------- > From: Carroll Waddell > > > Was anyone in the group in on the development of the H8-5. > > I'm trying to build an interface that will connect to the serial > port of > > a PC and then emulate 2 tape recorders, then connect these to the 2 > > phono ports on the H8-5 so that data can be sent/received > between the > > H8-5 and the PC. > > > > What I've done so far LOOKS like it should work. But it doesn't > > Carroll > > -- > > Delivered by the SEBHC Mailing List > > If you would like to unsubscribe, please send the word > "unsubscribe" > > in the **body** of a message to sebhc-request@sebhc.org. > Let me go into a little more detail. I have all the heathkit tape images stored in my PC. I stored them there years ago when I stopped using the H8. Last year, I retrieved them back into the H8 then transferred them to actual cassette tapes. I know the images from my PC are good, because the real cassette tapes will now load and work fine. But what I want to do is to connect the serial port on my PC to an FSK modulator to create the 1200 Hz and 2400 Hz audio tones that can be fed into the H8-5 tape input jack. The device should convert the serial data to audio tones for the H8-5 and they should be identical to the tones from an actual tape. I built up an FSK modulator that is just like the one on the H8-5 board. I feed a 4800 Hz square wave to 2 J-K flip flops (74LS131 I think). At any rate I am using the same circuit that Heath put on the H8-5 card. I am watching the audio on my scope, and it looks identical to the wave shown on the Heath waveform drawings. Only 1 time in my trials did it even start to load. The rest of the time it does nothing. This project is 1 part of a project that I am working on to us a PC to emulate an H19, a serial printer, and 2 cassette machines. I've gotten the H19 and serial printer emulation working. Now, I'm working on the cassette emulation. Thanks for the response. Carroll --------------060404080904050403060003 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit davidwallace2000@comcast.net wrote:

The hardest part of a tape cassette interface is keeping the phase and amplitude consistent across the frequency band. You MUST be using a hi-fi recorder. Otherwise, you'll get significant zero-crossing shift (which will make the pulse widths for zero and one different when you have a sequence of "0,1"; a sequence of "0,0"; a sequence of "1,0" and a sequence of "1,1".

If you can, "loop back" from transmit data to receive data and see if this "null tape device" will successfully transmit the data. If it does, your recorder is probably at fault. If not, I have all the H8-5 documents and a fairly good understanding of PLL technology.

-------------- Original message --------------
From: Carroll Waddell <carrollwaddell@sc.rr.com>

> Was anyone in the group in on the development of the H8-5.
> I'm trying to build an interface that will connect to the serial port of
> a PC and then emulate 2 tape recorders, then connect these to the 2
> phono ports on the H8-5 so that data can be sent/received between the
> H8-5 and the PC.
>
> What I've done so far LOOKS like it should work. But it doesn't
> Carroll
> --
> Delivered by the SEBHC Mailing List
> If you would like to unsubscribe, please send the word "unsubscribe"
> in the **body** of a message to sebhc-request@sebhc.org.

Let me go into a little more detail. I have all the heathkit tape images stored in my PC. I stored them there years ago when I stopped using the H8. Last year, I retrieved them back into the H8 then transferred them to actual cassette tapes. I know the images from my PC are good, because the real cassette tapes will now load and work fine.
But what I want to do is to connect the serial port on my PC to an FSK modulator to create the 1200 Hz and 2400 Hz audio tones that can be fed into the H8-5 tape input jack. The device should convert the serial data to audio tones for the H8-5 and they should be identical to the tones from an actual tape.
I built up an FSK modulator that is just like the one on the H8-5 board. I feed a 4800 Hz square wave to 2 J-K flip flops (74LS131 I think). At any rate I am using the same circuit that Heath put on the H8-5 card. I am watching the audio on my scope, and it looks identical to the wave shown on the Heath waveform drawings.

Only 1 time in my trials did it even start to load. The rest of the time it does nothing.

This project is 1 part of a project that I am working on to us a PC to emulate an H19, a serial printer, and 2 cassette machines. I've gotten the H19 and serial printer emulation working. Now, I'm working on the cassette emulation.

Thanks for the response.
Carroll
--------------060404080904050403060003-- -- Delivered by the SEBHC Mailing List If you would like to unsubscribe, please send the word "unsubscribe" in the **body** of a message to sebhc-request@sebhc.org.