PA Chime Generator - Revision history

Matt Parnell at 23:43, 26 August 2021

2021-08-26T23:43:38Z

← Older revision		Revision as of 23:43, 26 August 2021
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	While these parts are pin-for-pin compatible, and seemingly listed as drop-in replacements, there is no doubt that the BXA4230K has a distinctly different sound than the BT8040N. The tone progression interval, pacing and decay (with external circuits) are very similar. The BX4230K, however, has lower fundamental tones, and additional harmonics and/or sustained tones. I don't have captured audio samples - but I can say that if you've heard the PA-9100RC chime, you won't be satisfied with the BT8040N. I wasn't.		While these parts are pin-for-pin compatible, and seemingly listed as drop-in replacements, there is no doubt that the BXA4230K has a distinctly different sound than the BT8040N. The tone progression interval, pacing and decay (with external circuits) are very similar. The BX4230K, however, has lower fundamental tones, and additional harmonics and/or sustained tones. I don't have captured audio samples - but I can say that if you've heard the PA-9100RC chime, you won't be satisfied with the BT8040N. I wasn't.

			== Future ==

			The LCD display was primarily added to provide a visual level cue to the announcer. The PA microphone is very sensitive to proximity and volume; too far away or too quiet and the PA announcement isn't sufficiently audible. This seemed like a larger issue in 2020; as of 2021, though, the staff is doing quite well making clear announcements. The development semi-extensive code to add a graphical Vu meter (with louder/software cues) to the LCD seems unnecessary at this time.

			The hardware is mostly ready for feeding the microphone signal into a low-passed ADC input for microphone monitoring when and if this feature is ever to be developed.

Matt Parnell at 23:39, 26 August 2021

2021-08-26T23:39:50Z

← Older revision		Revision as of 23:39, 26 August 2021
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	* In April, a BT8040N was extracted from an eBay-purchased InterM PA-1000BR amplifier. While functional - the sound wasn't <i>quite right</i> (more on this below).		* In April, a BT8040N was extracted from an eBay-purchased InterM PA-1000BR amplifier. While functional - the sound wasn't <i>quite right</i> (more on this below).
	* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.		* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.
	* In August, a ~~BX4230K~~ came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.		* In August, a BXA4230K came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.

	== Design ==		== Design ==
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	When and if time permits, a final schematic will be produced to show the as-built hardware in its entirety.		When and if time permits, a final schematic will be produced to show the as-built hardware in its entirety.

			== BT8040N versus BXA4230K ==

			While these parts are pin-for-pin compatible, and seemingly listed as drop-in replacements, there is no doubt that the BXA4230K has a distinctly different sound than the BT8040N. The tone progression interval, pacing and decay (with external circuits) are very similar. The BX4230K, however, has lower fundamental tones, and additional harmonics and/or sustained tones. I don't have captured audio samples - but I can say that if you've heard the PA-9100RC chime, you won't be satisfied with the BT8040N. I wasn't.

Matt Parnell at 23:36, 26 August 2021

2021-08-26T23:36:06Z

← Older revision		Revision as of 23:36, 26 August 2021
Line 59:		Line 59:
	* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.		* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.
	* In August, a BX4230K came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.		* In August, a BX4230K came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.

			== Design ==

			The preliminary schematic shown in March is mostly accurate. Modification include (but are not limited to):

			* The addition of a C2000 microcontroller board (EVM), LCD, button and indicator LED (embedded in the button).
			* The addition of a bandpass filter and DC biasing, as is present in the Inkel PA-9100RC (as originally mentioned in February).
			* Power supplies to produce +5 V and +3.3 V for the analog and digital supplies, respectively.

			When and if time permits, a final schematic will be produced to show the as-built hardware in its entirety.

Matt Parnell: /* August 2021 */

2021-08-26T23:30:11Z

August 2021

← Older revision		Revision as of 23:30, 26 August 2021
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	=== August 2021 ===		=== August 2021 ===

	A switch failure on the PA microphone prompted re-visiting this project. The switch was fixed - but the chime generator was finished (in "beta" form, anyhow) as well. Some updates:		A switch failure on the PA microphone prompted re-visiting this project. The switch was fixed - but the chime generator was finished (in "beta" form, anyhow) as well.

			Some updates:

	* The BXA4240 sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.		* The BXA4240 sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.

Matt Parnell: /* August 2021 */

2021-08-26T23:30:02Z

August 2021

← Older revision		Revision as of 23:30, 26 August 2021
Line 51:		Line 51:
	=== August 2021 ===		=== August 2021 ===

	A switch failure on the PA microphone prompted re-visiting this project. The switch was fixed - but the chime generator was finished (in "beta" form, anyhow) as well.		A switch failure on the PA microphone prompted re-visiting this project. The switch was fixed - but the chime generator was finished (in "beta" form, anyhow) as well. Some updates:

	Some updates:

	* The BXA4240 sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.		* The BXA4240 sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.

Matt Parnell: /* August 2021 */

2021-08-26T23:29:13Z

August 2021

← Older revision		Revision as of 23:29, 26 August 2021
Line 55:		Line 55:
	Some updates:		Some updates:

	* The ~~<b>~~BXA4240~~</b>~~ sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.		* The BXA4240 sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.
	* In April, a ~~<b>~~BT8040N~~</b>~~ was extracted from an eBay-purchased InterM PA-1000BR amplifier. While functional - the sound wasn't <i>quite right</i> (more on this below).		* In April, a BT8040N was extracted from an eBay-purchased InterM PA-1000BR amplifier. While functional - the sound wasn't <i>quite right</i> (more on this below).
	* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.		* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.
	* In August, a ~~<b>~~BX4230K~~</b>~~ came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.		* In August, a BX4230K came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.

Matt Parnell: /* August 2021 */

2021-08-26T23:28:55Z

August 2021

← Older revision		Revision as of 23:28, 26 August 2021
Line 55:		Line 55:
	Some updates:		Some updates:

	* The BXA4240 sourced from China was a bust. A scam ~~of sorts~~ (received a random phone case). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.		* The <b>BXA4240</b> sourced from China in February was a bust. The transaction turned out a scam (received a random phone case instead of the IC). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.
			* In April, a <b>BT8040N</b> was extracted from an eBay-purchased InterM PA-1000BR amplifier. While functional - the sound wasn't <i>quite right</i> (more on this below).
	(~~to be continued~~)		* A Texas Instruments C2000 evaluation board was selected as the "brains" per familiarity in the designer's day job. Over the course of months, code was written to control the chime, microphone mute, button LED and a small LCD display via button trigger. The code functionality is described in more detail in a separate section.
			* In August, a <b>BX4230K</b> came onto the market via eBay, extracted from an Inkel PA-9100RC (the exact model previously owned by Fairway). This chip <i>sounds exactly right</i>.

Matt Parnell: /* Project Status */

2021-08-25T11:53:43Z

Project Status

← Older revision		Revision as of 11:53, 25 August 2021
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	This project has been on hold due to other priorities. At this point, it's possible that its introduction may be delayed to the 2022 season.		This project has been on hold due to other priorities. At this point, it's possible that its introduction may be delayed to the 2022 season.

			=== August 2021 ===

			A switch failure on the PA microphone prompted re-visiting this project. The switch was fixed - but the chime generator was finished (in "beta" form, anyhow) as well.

			Some updates:

			* The BXA4240 sourced from China was a bust. A scam of sorts (received a random phone case). While AliExpress finally issued a full refund, it certainly doesn't reflect well upon the integrity of its sellers.

			(to be continued)

Matt Parnell: /* Project Status */

2021-07-29T13:35:19Z

Project Status

← Older revision		Revision as of 13:35, 29 July 2021
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	* A P-channel JFET based soft mute circuit has been added. The intent is to eliminate the use of the switch on the microphone (which creates an audible click/pop over the PA). This will also prevent passing audio from the microphone until the tone progression (chime) has completed.		* A P-channel JFET based soft mute circuit has been added. The intent is to eliminate the use of the switch on the microphone (which creates an audible click/pop over the PA). This will also prevent passing audio from the microphone until the tone progression (chime) has completed.
	* A single-ended output (RCA connector) will be used to connect to the JBL mixer-amplifier.		* A single-ended output (RCA connector) will be used to connect to the JBL mixer-amplifier.

			=== July 2021 ===

			This project has been on hold due to other priorities. At this point, it's possible that its introduction may be delayed to the 2022 season.

Matt Parnell: /* March 2021 */

2021-03-25T20:51:35Z

March 2021

← Older revision		Revision as of 20:51, 25 March 2021
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	Key features:		Key features:

	* Implementation of the ~~BXA8240~~ (consider "BT8040x" to be used interchangeably) in a manner similar to that shown in the interM schematics.		* Implementation of the BXA4240 (consider "BT8040x" to be used interchangeably) in a manner similar to that shown in the interM schematics.
	* The bandpass filter on the output of the ~~BXA8240~~ is still TBD. The gain and corner frequencies may need to be adjusted based upon bench measurements. The datasheet does not provide clear guidance on the output signal of this device.		* The bandpass filter on the output of the BXA4240 is still TBD. The gain and corner frequencies may need to be adjusted based upon bench measurements. The datasheet does not provide clear guidance on the output signal of this device.
	* A P-channel JFET based soft mute circuit has been added. The intent is to eliminate the use of the switch on the microphone (which creates an audible click/pop over the PA). This will also prevent passing audio from the microphone until the tone progression (chime) has completed.		* A P-channel JFET based soft mute circuit has been added. The intent is to eliminate the use of the switch on the microphone (which creates an audible click/pop over the PA). This will also prevent passing audio from the microphone until the tone progression (chime) has completed.
	* A single-ended output (RCA connector) will be used to connect to the JBL mixer-amplifier.		* A single-ended output (RCA connector) will be used to connect to the JBL mixer-amplifier.